Gazes, Words, and Silences in Pragmatics 9783031425707, 9783031425714

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Perspectives in Pragmatics, Philosophy & Psychology 36

Paola Pennisi

Gazes, Words, and Silences in Pragmatics

Perspectives in Pragmatics, Philosophy & Psychology Volume 36

Series Editor Alessandro Capone, University of Messina, Messina, Italy Editorial Board Members Noel Burton-Roberts, Newcastle University, Newcastle, Australia Brian Butler, University of North Carolina Asheville, Asheville, NC, USA Marco Carapezza, Università degli Studi di Palermo, Palermo, Italy Felice Cimatti, University of Calabria, Cosenza, Italy Eros Corazza, Carleton University, Ottawa, Canada Michael Devitt, City University of New York, New York, NY, USA Frans van Eemeren, University of Amsterdam, Amsterdam, The Netherlands Neil Feit, SUNY Fredonia, Fredonia, NY, USA Alessandra Giorgi, University of Venice, Venice, Italy Larry Horn, Yale University, New Haven, CT, USA Klaus von Heusinger, University of Cologne, Cologne, Germany Kasia Jaszczolt, University of Cambridge, Cambridge, UK Robin Beth Jeshion, University of Southern California, Los Angeles, CA, USA Kepa Korta, University of the Basque Country, Leioa, Spain Ernest Lepore, Rutgers University, New Brunswick, NJ, USA Stephen C. Levinson, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands Francesca Piazza, Università degli Studi di Palermo, Palermo, Italy Mark Richard, Harvard University, Cambridge, MA, USA Nathan Salmon, University of California at Santa Barbara, Santa Barbara, CA, USA Stephen R. Schiffer, New York University, New York, NY, USA Michel Seymour, Université de Montréal, Montreal, Canada Mandy Simons, Carnegie Mellon University, Pittsburgh, PA, USA Timothy Williamson, University of Oxford, Oxford, UK

Anna Wierbizcka, Australian National University, Canberra, Australia Elizabeth C. Traugott, Stanford University, Stanford, CA, USA Advisory Editors Sanford Goldberg, Northwestern's Weinberg College of Arts and Sciences, Evanston, IL, USA Roberto Graci, University of Messina, Messina, Italy Fabrizio Macagno, New University of Lisbon, Lisbon, Portugal Yael Sharvit, UCLA, Los Angeles, CA, USA Keith Allan, Monash University, Melbourne, Australia Louise Cummings, The Hong Kong Polytechnic University, Hung Hom, Hong Kong Wayne A. Davis, Georgetown University, Washington, DC, USA Igor Douven, University of Paris-Sorbonne, Paris, France Istvan Kecskes, State University of New York at Albany, Albany, NY, USA Antonino Pennisi, University of Messina, Messina, Italy Francesca Santuli, Ca' Foscari University of Venice, Venice, Italy

Perspectives in Pragmatics, Philosophy and Psychology deals with theoretical pragmatics and pragmatics from a philosophical point of view. The connection between philosophy and pragmatics is double. On the one hand, philosophy contributes to creating a framework to be called the ‘pragmatics of language’ capable of dealing with interpretation phenomena that complement purely semantic processes; on the other hand, pragmatics is capable of coping with major philosophical problems, e.g. skepticism and Gettier’s problem. All volumes in the collection reserve a central place for the philosophical ideas in pragmatics, such as contributions to epistemology in which pragmatics plays a key role.

*** This series is indexed by Scopus The collection: Perspectives in Pragmatics, Philosophy and Psychology publishes: • pragmatics applied to philosophical problems and in the area of pragmalinguistics • pragmatics applied to the understanding of propositional attitudes, including knowledge, belief, in dissolving paradoxes and puzzles relating to epistemology • pragmatics applied to psychology, especially on the topic of intentions and mindreading • philosophical treatments of dialogue analysis

Paola Pennisi

Gazes, Words, and Silences in Pragmatics

Paola Pennisi Dipartimento di Patologia Umana dell’Età Adulta e dell’Età Evolutiva Università degli Studi di Messina Messina, Italy

ISSN 2214-3807 ISSN 2214-3815 (electronic) Perspectives in Pragmatics, Philosophy & Psychology ISBN 978-3-031-42570-7 ISBN 978-3-031-42571-4 (eBook) https://doi.org/10.1007/978-3-031-42571-4 © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland Paper in this product is recyclable.

Acknowledgments

I would like to express my gratitude to many people who have helped me along. Thanks to the colleagues of the Department of Cognitive Sciences, for having created that stimulating and competitive environment which provides fertile ground for the birth of new curiosities and new ideas: Rosalia Cavalieri, Antonino Bucca, Francesco Parisi, Sebastiano Nucera, Alessandra Falzone, Carmelo Porto, Carmelo Vicario, Valentina Cardella, Alessandro Capone, Caterina Scianna, to name just a few of them. A special thanks also goes to Donata Chiricò for the passion with which she enriched me with her point of view on sign languages; to Claudio Paolucci for his always attentive suggestions on the contribution of semiotics to the cognitive sciences; to Michela Cannarozzo, for constantly providing me with precious insights into autism, through her clinical experience; to dr. Francesco Galletti, Angela Alibrandi and Patrizia Longo for the welcome and availability always shown towards to the other colleagues of the Department of Human Pathology of adulthood and developmental age. Thanks to the CUMO of Noto: to the president Rosario Pignatello, to the director Nella Aglieco, and to all the staff who work constantly to provide us with an efficient and beautiful venue, in which it has been possible to host over time numerous conferences of the Coordination of Italian Doctorates in Cognitive Sciences (CODISCO), which was attended by some of the most authoritative scholars in the field of Cognitive Sciences and whose points of view have constantly fueled new curiosities in me: David Freedberg, Frans de Waal, Telmo Pievani, Alessandro Minelli, Giorgio Vallortigara, Douglas Hofstadter, Vittorio Gallese, Mark Turner, to name just a few of them. I thank Kamesh Senthilkumar and the crew at Springer for their interest in my book. And finally, the biggest thanks goes to my family; especially to my father, for having taught me by example that the love of life is the unselfish and insatiable love of research, in all of its forms. To my mother and Ezio for their constant support and patience, without which I certainly would have lost my way. To my son Giuseppe, who teaches me every day what joy is. Paola Pennisi Catania, 26 Dicembre 2022 v

Contents

1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Linguistic Gazes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 1 4

2

The Communicative Eyes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1 A Unique Eye Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Subcortical Vision at Birth . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Neonatal Socialization through Eyes . . . . . . . . . . . . . . . . . . . . . 2.4 Development of the Visual Social Cognition . . . . . . . . . . . . . . . 2.5 The Cultural Habits of Eye-Contact . . . . . . . . . . . . . . . . . . . . . . 2.6 Innate and Acquired Skills . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . .

5 5 6 7 9 12 13 13

3

Emotional Tears: A Human Uniqueness . . . . . . . . . . . . . . . . . . . . . . 3.1 The Cognitive Role of Human Tears . . . . . . . . . . . . . . . . . . . . . . 3.2 Tears in Other Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Tears as Individual Relief . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Social Theories on Emotional Tears . . . . . . . . . . . . . . . . . . . . . . . 3.5 Weapons of the Weak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.1 A Way for the Linguistic Thinking . . . . . . . . . . . . . . . . . . 3.5.2 A Collateral Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.3 Culture and Tears . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5.4 Authenticity Does Not Necessarily Mean Others’ Help . . . . 3.6 The Weapon of Truth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

17 17 18 20 21 22 23 24 25 27 31 32

4

Eyes, Gazes and Language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Face to Face with Mummy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Cooperative Gazes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.1 Individual Intentionality and Shared Intentionality . . . . . . 4.2.2 Cooperative Gaze, Lying Gaze . . . . . . . . . . . . . . . . . . . .

35 35 36 37 40

. . . . .

vii

viii

Contents

4.3 4.4

The Gaze Advantage: Empirical Studies . . . . . . . . . . . . . . . . . . . . And So? What Happens to the Link Between Gazes and Language? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

41 45 46

What Does We Share with Other Animals? . . . . . . . . . . . . . . . . . . . 5.1 Phylogenetic Development of Eyes’ Meaning . . . . . . . . . . . . . . . . 5.2 Three Ways of Looking at Looks . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 Social Structure and Body Structure Influence the Use of Indexical Cues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 Gaze Following in Non-human Primates . . . . . . . . . . . . . . . . . . . 5.4.1 Hippies Versus Warmongers . . . . . . . . . . . . . . . . . . . . . . 5.5 Double Gazes Are Not a Human Uniqueness . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

49 49 52

Why Gazes Are Not So Special . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 A Special Breath and a Special Vocal Tract . . . . . . . . . . . . . . . . 6.2 All Sensory Pathways Lead to Mom, but Hearing Is the Fastest . . 6.3 Loving Gazes Even among Other Primates . . . . . . . . . . . . . . . . . 6.3.1 The Sense of Selfhood in Chimpanzees and in Humans . . 6.4 Language Development without Mutual Gazes . . . . . . . . . . . . . . 6.5 Language Development with Sporadic Joint Attention . . . . . . . . . 6.6 The Need for Communication and the Intentional Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . .

73 73 77 80 83 85 88

. .

91 92

7

My Body Decides What I Can Do . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Ostensive Act + Referential Act = Intention to Communicate . . . 7.2 What Talking Parrots Have to Say on the Topic . . . . . . . . . . . . . 7.3 And the Hand Created the Intention . . . . . . . . . . . . . . . . . . . . . . 7.4 The Only Talking Creatures in the Universe . . . . . . . . . . . . . . . . 7.5 A Radical Embodied Perspective . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . .

97 97 98 100 102 104 105

8

Lateralization of Handedness and Language . . . . . . . . . . . . . . . . . . . 8.1 What Is the Hemispheric Lateralization . . . . . . . . . . . . . . . . . . . . 8.2 The Lateralization of Language . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.1 Lateralization of Acoustic Signals Emerged before Primates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.2 Lateralization of Acoustic Communication in Non-human Primates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.3 Lateralization of Vocal Communication in Humans . . . . . . 8.3 Lateralization of Handedness . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.3.1 Did Limb Lateralizations Exist before Primates? . . . . . . . .

107 107 109

5

6

54 56 61 65 67

109 111 113 115 117

Contents

ix

8.3.2

Relationship Between Hand Dominance and Lateralization of Vocal and Gestural Communication Behaviors in Primates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4 Relationship Between Language Lateralization and Hand Dominance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5 What Is the Lateralization of a Function for? . . . . . . . . . . . . . . . . 8.6 Relationship among Lateralization, Use of Hand and Language . . . 8.7 Relationship Between Manipulation and Language during the Ontogenetic Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8 Sign Languages: Differences Between the Ontogenetic Plane and the Phylogenetic Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

119 121 121 124 127 128 129

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

Chapter 1

Introduction

1.1

Linguistic Gazes

The object of this study is the relationship between communication by the eyes and language. Naturally such a study, by its nature, fully crosses the theme of reading the mind of the other. But why dedicate a text on the philosophy of language to the study of communication by gazes? Eyes are special for so many reasons. First of all, a gaze fixed on us has the power to immediately arouse the sensation of its existence, even if our attention is directed elsewhere. We have some sort of cerebral sensor that tells us that someone is watching us. It is a wild instinct that derives directly from our dual nature of prey (which must understand if the rest of the pack sees danger) and predator (which must understand where its prey is looking). We instinctively perceive—knowingly or unknowingly—the presence of other eyes around us, and this profoundly alters our thoughts, our movements, and our own perceptions. The awareness of the presence of gazes around us modify our attentional processes and forces us to deal with the eyes of the other, whether we like it or not. The representations of this phenomenon, sometimes only intuited and sometimes analytically investigated by philosophers, have given rise to hundreds of works that later became cornerstones of Western culture. Nathaniel Hawthorne describes as a puritanical community’s punishment for the beautiful adulteress Hester Prynne, the penalty of being exposed to the public eye for a few hours wearing the proof and condemnation of her shameful sin: her baby girl and a scarlet letter sewn on her breast. The latter to be worn forever, so that no one could look even for a minute at Hester Prynne without remembering that she was an adulteress: “The unhappy culprit sustained herself as best a woman might, under the heavy weight of a thousand unrelenting eyes, all fastened upon her, and concentrated at her bosom. It was almost intolerable to be borne” (Hawthorne, 1850, Chapter 2). The eye is not only the gateway to the other, but it is also an indication of his presence and of our presence in front of him: we are present to the attention of those who look at us. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Pennisi, Gazes, Words, and Silences in Pragmatics, Perspectives in Pragmatics, Philosophy & Psychology 36, https://doi.org/10.1007/978-3-031-42571-4_1

1

2

1

Introduction

The second reason that drives us to consider the eyes so special is that we usually recognize a very strong expressive and communicative power to them. Also from this point of view, looking and being looked at have always been the subject of philosophical investigations and literary reveries. Saramago, through the mouth of an ophthalmologist who became blind, describes the eyes as the last part of the body in which a soul is still left (Saramago, Blindness, p. 79). But Saramago goes beyond saying, through the mouth of the doctor’s wife, (a character who seems to understand reality better than the others because she is the only sighted person in a world of blind people) that without eyes, the nature of our feelings would change: Poor woman, Your poor parents, poor you, when you meet up, blind in eyes and blind in feelings, because the feelings with which we have lived and which allowed us to live as we were, depended on our having the eyes we were born with, without eyes feelings become something different, we do not know how, we do not know what (Saramago, 1997, p. 93).

In a species that also uses looks to orient themselves emotionally, those who don’t have eyes for feelings still manage to see through the eyes of others; but if the whole species loses this ability, then the very nature of feelings will change. She too will soon lose the ability to understand others through sight because this type of sight feeds on the gaze of others: “I’ll see less and less all the time, even though I may not lose my eyesight I shall become more and more blind because I shall have no one to see me” (ibid., p. 117). In the communication of human feelings, ambiguity is not only given by the crossing of signals coming from the five senses, as it is for many other animals, but also by the presence of meanings. Feelings and meanings are closely intertwined. Communication through the eyes and that which is expressed in language are often opposed by literature. Saramago, for example, contrasts them on the level of truth by observing that with time “we made our eyes into a kind of mirror turned inwards, with the result that they often show without reserve what we are verbally trying to deny” (ibid., p. 9). In the nineteenth century, however, Mary Shelley, in her apocalyptic novel The Last Man, described this relationship by contrasting the fleeting ambiguity of the gaze with the stumbling but peremptory irrevocability of words when, telling of a brother who must communicate to his sister Perdita the death of the man whom she loves: the words died before I could articulate them; I felt a ghastly smile wrinkle my lips. She understood my gesture; again her head fell; again her fingers worked restlessly. At last I recovered speech, but my voice terrified her; the hapless girl had understood my look, and for worlds she would not that the tale of her heavy misery should have been shaped out and confirmed by hard, irrevocable words (Shelley 1826, p. 159).

But this juxtaposition seems to create a basic ambiguity. It is not that feelings are mediated by eyes and reason by words; is that words convey a different order of feelings and meanings. An order where the transience of glances leaves room for the intrusion of feelings and meanings stratified in memory, with their contradictions, resulting in the unpredictable behavior of the human being: Words are like that, they deceive, they pile up, it seems they do not know where to go, and, suddenly, because of two or three or four that suddenly come out, simple in themselves, a

1.1

Linguistic Gazes

3

personal pronoun, an adverb, a verb, an adjective, we have the excitement of seeing them coming irresistibly to the surface through the skin and the eyes and upsetting the composure of our feelings, sometimes the nerves that cannot bear it any longer, they put up with a great deal, they put up with everything, it was as if they were wearing armour, we might say. The doctor’s wife has nerves of steel, and yet the doctor’s wife is reduced to tears because of a personal pronoun, an adverb, a verb, an adjective, mere grammatical categories, mere labels, just like the two women, the others, indefinite pronouns, they too are crying, they embrace the woman of the whole sentence (Saramago, 1997, p. 104).

With the development of language, analogical thinking has been associated with the habit of digital thinking where the coexistence of many meanings or many feelings is expressed with a single communicative act. In man, language has pervaded the world of feelings with its meanings; this has made the looks we give our species mates linguistic looks; that is, gazes already dominated by the cognitive structuring of thought brought about by the development of language. We can’t see a person’s eyes without seeing the eyes of our mother, or our teacher, or of the man who stole our car. We cannot look into a person’s eyes without associating with that gaze the meaning of his exploratory gesture: “he is looking at my plate to see if I have eaten and therefore if I have liked the food he has prepared for me.” With a single glance, we trigger a recursive process of reading the other’s mind that we are unable to inhibit with our will; that is, a recursive process of mind reading that is almost uncontrollable or in any case difficult to manage. In this book, we will try to show that the almost mystical powers that we usually attribute to the eyes derive in some way from our ontology of talking animal species. The work will take place by alternating reflections inspired by philosophical theories that attempt to link the development of language to communication through the eyes, with comparative analysis of empirical data on the study of human and animal behavior. The answer that this work tries to provide to the questions raised by the studies on the relationship between the development of language and the communicative use of gazes emphasizes two aspects: one is the subordination of communication through gazes to the logics that the language imposes on our cognition; the second is instead that the most original communicative element of the human eye compared to that of other animals is the tear triggered by emotional (and not physiological) factors. Even in the latter case, however, the reasons that phylogenetically led such a costly behavior in terms of dehydration of the organism and energy expenditure to develop in the human species is precisely the need to communicate reliability of the information in spite of the ambiguity of human signals. Ambiguity is brought to the highest levels of expression precisely by language and by the possibility of using it together with other forms of communication. The text consists of seven chapters. The first one describes the ontogenetic development of communication through gazes: it explains what is peculiar in the anatomy of the eye of the genus homo; the development of the ability to communicate through gazes and to perceive social information in the gazes of others is described; the cultural differences in the acquisition of this type of competence are analyzed and finally the age-old question nature/culture is addressed in relation to the reading of others’ gazes.

4

1

Introduction

In the second chapter, the question of tears is addressed: also in this case we proceed with the description of human peculiarity; secondly, however, the theories existing in the literature are described and discussed to explain why man is the only animal that associates tears with feelings; finally, it argues in favor of the unedited thesis according to which tears are the attestation of the reliability and importance of the information they are associated with. The third chapter describes the theses of Herbert Terrace and Michael Tomasello in relation to the interactions between the communicative use of gaze and the development of language in humans. In the fourth chapter, through an in-depth study of the ethological literature on the use of the gaze in other animals, it is shown how the human species is not the only one that can use the gaze to read the minds of other individuals. It will be shown how the differences found between humans and the primates closest to us in the communicative use of the gaze are a consequence, and not a cause, of the development of language. In the fifth chapter, it will be shown that in reality the communicative use of the gaze is not, contrary to the presence of a supralaryngeal vocal tract with the characteristics of the human one, a prerequisite for the development of language. This demonstration will mainly make use of the observation of language development in two special cases: the case of congenital blindness and that of autism, where—for different reasons—the subjects learn to acquire language without using those attentional hot-spots created in typically developing children by eye games with caregivers. In the sixth chapter, however, we will try to emphasize the importance of another part of the human body for the development of language: the hand. The hand and language share the ability to actively manipulate (and not passively receive) the world. With the manual exploration of the world, the child immediately learns to distinguish between self and other-than-self. The hand and the supralaryngeal vocal tract thus become two bodily devices capable of promoting the development of neuro-cerebral structures that allow us to think pro-actively about the world, effectively making man a creator of new worlds. In the seventh chapter, through the study of how the lateralization of language on the left and the average dominance of the right hand have evolved phylogenetically in the human population, we tried to provide indirect evidence of the independence of these two body-cognitive systems, and at the same time of their intrinsic relationship: two independent but complementary systems that collaborate in the manipulation of the world.

References Hawthorne, N., (1850). The scarlet letter. Saramago, J. (1997). Blindness. (J. Sager, Trans.). The Harvill Press. Shelley, M. W. (1826). The Last Man. McWhir, A. (ed.) (1996), Toronto: Oxford University Press.

Chapter 2

The Communicative Eyes

2.1

A Unique Eye Anatomy

With our eyes we usually transmit two types of information: information concerning our mental states (emotions, intentions, etc ...) and information on our attentional focus. The eyes of human beings, compared to those of other animals, appear more expressive due to some characteristics that are specific of humans, effectively described in 2001 by Kobayashi and Kohshima. The two authors, after comparing the morphological conformation of the eye of almost half of the known species of primates, found some unique characteristics compared to the rest of the animal world: (1) humans have a white sclera, this makes clearly visible the difference between the iris (which obviously includes the pupil) and sclera; (2) the sclera is exceptionally large in humans in proportion to the overall size of the eye and finally (3) the human sclera is exceptionally developed horizontally. What is the significance of these peculiarities? The authors excluded that the differences in the shape of the eye were related to visual functions. On the contrary, the amount of exposed sclera appears to be linked to the size of the animal: the higher the height at which the animal places its head while walking, the greater the portion of the sclera exposed and the smaller the size of the iris. According to the authors, this correlation should be explained by the fact that moving the head for vision adjustments (centering the subject, widening the scene, etc ...) is much more expensive if the head is heavier (due to the increase in size and the greater distance from the ground); moving just the eyes is much less expensive. Furthermore, taller animals usually have a wider head and therefore there is often more space for the muscles that allow the movement of the eyes. Moreover, the transition to terrestrial life greatly benefits from the possibility of visually exploring the entire horizontal axis. Finally, the whiteness of the human cornea contrasts with the dark pigmentation of that of most primates. Since the dark pigmentation of the cornea has costs in terms of energy, it must be associated with some advantage in terms of the fitness of the species and the most likely hypothesis is that it helps to mask the direction of the © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Pennisi, Gazes, Words, and Silences in Pragmatics, Perspectives in Pragmatics, Philosophy & Psychology 36, https://doi.org/10.1007/978-3-031-42571-4_2

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2 The Communicative Eyes

gaze from predators. Only man, among the primates, has a conformation of the eye that allows you to clearly establish where it is looking. When the sclera is dark, that is, in non-human primates, it is extremely difficult to see from a distance where the individual is looking exactly; on the contrary, the fact that in men there is a large white sclera, according to the authors of the study, is to be interpreted in the light of the potential evolutionary advantage that is obtained from the facilitation of intraspecific communication. The fact that the sclera is wide and that it is very wide especially horizontally is an advantage because it enormously extends the visible range of the species. The authors conclude that the morphological uniqueness of the human eye compared to that of other primates is that it allows you to communicate through simple glances. A few years later, probably encouraged by the wide interest of scholars on the origin of human communication for the subject, Kobayashi and Hashiya (2011) developed the idea that through mutual gaze humans practice a sort of remote grooming. The grooming is a practice that primates use to keep the group cohesive: individuals with a strong social bond, both parental and friendly, caress, massage and clean each other’s fur and this strengthens their bond.

2.2

Subcortical Vision at Birth

An effervescent gurgling of intestinal swarms, a rhythmic and reassuring heartbeat, a vibrant and warm voice and finally the humid warmth of amniotic fluids are the sensory world of man before the earthquake of childbirth disturbs the placid stillness. At birth and for the first 2 months of life, vision in newborns is controlled at the subcortical level (Bronson, 1974). This hypothesis, dating back to the 1970s, is confirmed both by studies on ontogenetic development and by numerous data of a clinical nature. At the level of ontogenetic development, the strong evidence in favor of this idea is that the neocortical areas normally associated with visual functions are usually immature at birth (Atkinson, 2008; Born et al., 2002); on the other hand, the subcortical ones are already quite developed (Johnson, 1990). Furthermore, as we will see in the next paragraph, newborns at birth already have a marked preference for human faces, then the preference for faces is the effect of the activity of subcortical mechanisms (Simion et al., 1998; Johnson, 2005). Looking at the clinical data, we can first of all say that newborns with extensive lesions in the occipital cortex have normal ability to fix and track a visual target (Dubowitz et al., 1986). Infants with congenital lesions to the basal ganglia (Mercuri et al., 1997) or to the thalamus (Ricci et al., 2006) also show abnormalities of visual function. Finally, another interesting clinical data is provided to us by infants with severe forms of cystic leukomalacia. This condition is associated with preterm birth weighing less than 1500 grams; it involves cavitation of the white matter at birth with the presence of microscopic necrotic areas. Then, children born with this

2.3

Neonatal Socialization through Eyes

7

pathology normally show a cortical blindness as they grow up, but despite this they are able to recognize and prefer human faces up to 48 weeks of age (Ramenghi et al., 2010). The subcortical processing of faces probably leads to a holistic perception of the stimulus (Almasi & Behrmann, 2021). This means that infants (and in part also adults) see the face as if it were a single stimulus: they integrate all the parts of a face simultaneously into a single perceptual configuration. The view of details of the face or parts of the face separated from the whole (eyes / nose / mouth) will not be recognized as part of a face.

2.3

Neonatal Socialization through Eyes

The babies of Homo sapiens sapiens are extremely sensitive to eye contact. In Fig. 2.1 it is possible to see summarized the main stages of the development of visual socialization in newborns. They open their eyes within the first 20 minutes of their life (Lamberg, 1981) and soon after they are already able to follow moving stimuli, but are much more accurate in doing so if these stimuli are or have the appearance of human faces (Goren et al., 1975; Maurer & Young, 1983; Johnson et al., 1991; Valenza et al., 1996). Recently some empirical findings obtained by the projection of visual stimuli through the uterine wall seem to suggest that this preference to face-like stimuli is present at the thirty third week of pregnancy (Reid et al., 2017). Newborns are sensitive to the play of light that affects the faces they observe already between 13 and 168 hours of life (Farroni et al., 2005). Already at about 36 hours of age (but probably even earlier) they prefer faces with open eyes rather than closed ones (Batki et al., 2000). Between 24 and 120 hours of life they have a clear preference for social visual stimuli (Salva et al., 2011). Between 2 and 5 days of life they seem to be able to notice if the person watching them is doing it directly or through their peripheral vision (Farroni et al., 2002). Infants also seem to prefer the faces of those who look directly at them rather than those of who do not look at them (Farroni et al., 2006; Farroni et al., 2002). It has also been shown that at 4 months, the cortical response to the vision of conspecific faces becomes stronger in newborns if the stimuli have gazes directed towards the subject rather than gazes directed elsewhere (Farroni et al., 2004). There are several authors who believe that preferential attention to the gazes directly turned towards the subject is a fundamental moment in the ontogenetic development of social cognition (Frischen et al., 2007). Recently some empirical studies have questioned the idea that the vision of newborns is entirely subcortical, and the hypothesis has been advanced that the cortical network of adulthood which is normally associated with the function of recognition, attention and perceptual processing of the face of others is the same that pushes infants to be attracted to the face of other co-specifics (Buiatti et al., 2019). This last thesis, if confirmed, would subvert the most recent theories on visual perception in newborns on many aspects, but not on the question of their preference

2

Fig. 2.1 The ontogenetic stages of the first visual social orienting

8 The Communicative Eyes

2.4

Development of the Visual Social Cognition

9

for the faces of other co-specifics: that it is exclusively linked to subcortical mechanisms, or that it affects the neocortex, at the beginning of its development, this propensity is innate. Although this propensity was first demonstrated in 1975 by Goren and his research team, it became more debated in the 1990s, when the two philosophical implications it carried with it were more deeply realized: (1) infants had innate skills; (2) the faces had a unique status, that is, they were not as elaborate as the other stimuli, but appeared encysted in a modularist cognitive logic.

2.4

Development of the Visual Social Cognition

Certainly faces have a unique perceptual status for the human species: if most mammals primarily use smell or hearing for the recognition of other conspecifics, in primates the visual component has assumed a leading role. The visual information offered by faces is conveyed by traits (gender, race, attractiveness, age, identity) and states (emotional, intentional). The interpretation of information is a very complex activity and the first cognitive tool that nature gives us at birth is not able to provide us with all these nuances. The ability to read a face develops as a result of experience and becomes efficient around 1 year of age, but becomes complete only in puberty (Pascalis et al., 2011). Now it will be described how the child learns to use his own gaze and that of others to fit into social life and understand it better and better. In Fig. 2.2 it is possible to find a graphic report of the main stages of this path. If the overall processing of the face therefore seems to follow a slow ontogenetic development, the search for the gaze of others is already present in more than 60% of newborns at 3 months of life and develops further in the following 5 months of life. The most macroscopic effect of this development is the progressive increase in the search for eye contact with the mother (or with the main caregiver) (Belini & Fernandes, 2010). Soon, eye contact seems to be able to enhance the cognitive processes to which it is associated, it becomes a sort of hot-spot for attention: a newborn remembers and identifies more easily an adult who has looked him in the eye (Farroni et al., 2002; Rigato et al., 2011). A 10/28-week-old infant is prompted to pay attention to the direction of an adult’s gaze (Hood et al., 1998); the data was also replicated at 4–5 months of age (Farroni et al., 2000). Furthermore, at 4 months the neural activity of newborns seems greater if they are directly looked at by their caregivers (Farroni et al., 2002). At about 5 months of age they develop a preference for larger eyes (Geldart et al., 1999); pay more attention to those objects that have been part of a triadic interaction in which the adult looked them in the eye (Parise et al. 2008) and are able to perceive minimal horizontal deviations (5 °) of the gaze in other individuals (Symons et al., 1998). At 6 months, they are followed by the gaze of an adult who first looks them in the eye or, alternatively, who addresses them with the baby talk (Senju & Csibra, 2008). This cognitive enhancement phenomenon becomes stronger and stronger as the child grows. For example, in 2006, Smith and co-workers showed that children are better at recognizing other people’s faces if they have gazes directed at them, but that this facilitation phenomenon is stronger in 10/

2

Fig. 2.2 The development of cognitive visual orienting

10 The Communicative Eyes

2.4

Development of the Visual Social Cognition

11

Visual scanning in infants 50 40 30 20 10 0 2 months

6 months

9 months

fixation time % eyes

12 months

15 months

18 months

24 months

fixation time % mouth

Fig. 2.3 Visual scanning in infants. The graphic show how many times children spent in fixing eyes (blue line) and mouth (orange line) during the ontogenetic development. These data are took from (Jones and Klin 2013)

11-years old children than 6/7 years-old ones. Therefore, already around 3/4 months of age, eye contact has the power to sharpen the cognitive finesse of the subject who perceives; probably this happens because eye contact modulates the level of activation of the social brain, that is the complex of cortical and subcortical regions that are involved in the processing of social information such as faces, gazes, biological movement, human action, goal orientation, theory of the mind and empathy (Senju and Johnson 2009). This cognitive modulation effect produced by the gaze of others is often called ‘the eye contact effect’ in the scientific literature and continues into adulthood. Although the eyes always remain the point of greatest fixation of the gaze during interactions with other conspecifics; during ontogenetic development there seems to be a critical period of slight decrease in interest: from birth to about 6–9 months of age, the interest in the eyes of others gradually and slowly increases; from 9 to 18 months of age there is a slight decrease of interest in the eyes, in favor of a slight increase in attention to the speaker’s mouth; after 18 months, the interest for eyes starts to increase again while the interest for the mouth decreases again (Jones and Klin 2013, cfr. Fig. 2.3). Despite this relative decrease in interest, between 12 and 18 months children begin to actively operate in order not to lose sight of the direction of the gaze of the person with whom they are interacting: Moll and Tomasello (2004) for example have shown that at this age, if a visual barrier that prevents children from seeing where the adult is looking arises, they will crawl until they free themselves from the visual impediment. Around 10 months of age, babies specialize in following the gaze rather than the orientation of the head to guide their attention towards what the other is looking at (Brooks & Meltzoff, 2002, 2005). At about 3–4 years of age, children begin to link mental states to the direction of gaze by assuming - for example - that if the mother looks at the glass of water on the table, the mother wants that glass of water (Baron-Cohen et al., 1995). At 3 years of

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2 The Communicative Eyes

age, children who receive conflicting information between the eyes and the words of an adult tend to prefer the linguistic message even if the correct or the most likely information was provided by the eyes. Instead, at 4–5 years of age, children are able to infer from the eyes of an adult whether he is lying or not (Freire et al., 2004). At age 6, and even more so at age 9, children tend to regard as a liar an adult who addresses them without looking into their eyes and this phenomenon is more evident in girls than in boys (Einav & Hood, 2008). The reflex of attention to the presence of gazes around oneself persists even in childhood: it has been experimentally found for example in children of about 11 years old (Senju et al., 2004), and indeed it seems to become more and more precise and sensitive to nuances as the child grows (Mareschal et al., 2016). Even at 8–12 years there are differences in the brain processing of faces between children and adults (Kimura et al., 2004; Kylliäinen et al., 2006). To all these studies it should also be added that the perception of the eyes of the newborn seems to have a very strong influence on the parental behavior of adults (Woo & Schaller, 2020). For example, in mothers of 7-month-old babies, a positive correlation was found between oxytocin levels and the duration of the looks exchanged with their baby (Kim et al., 2014).

2.5

The Cultural Habits of Eye-Contact

At this point, however, a clarification is urgent. Most of the studies just mentioned are carried out on children belonging mostly to highly industrialized countries. When, in 2004, Keller and collaborators published a study on parental styles conducted with the system of video encoding of spontaneous play sessions between caregivers and 3-month-old babies belonging to different cultures, a very interesting finding emerged. The children came from five different cultural communities: 26 children came from West Africa; 39 children from Gujarat (India); 21 children from Costa Rica; 51 children from Greece and 56 from Germany. Beyond the results they obtained on parental style (not relevant to our discussion), the interesting thing that emerged is that in the various peoples the percentage of interactions in which the researchers found a reciprocal look between caregiver and child differed enormously, oscillating from 58.97% in India to 100% in Germany. This data indicates that, although the mutual eye exchange is very important in all cultures, there is also a strong cultural difference in the importance attributed to it. To support this point of view there is also a study published in 1984 (but re-edited in 2009) conducted by Elinor Ochs and Bambi Schieffelin in which the ontogenetic development of children belonging to three different cultures was compared: the Anglo-American class average; the Kaluli (Papua New Guinea) and the Western Samoans. The study showed that socialization cannot be ascribed to a fixed and immutable pattern of behavior, but is subject to cultural and environmental differences in general. In relation to our reflections on the role of eye contact, it is interesting to note that according to the authors Kaluli mothers avoid long eye contact with their children

References

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and that in their culture this behavior is associated with witchcraft (Ochs & Schieffelin, 2009). In the age range from about 1 year to 7 years, cultural differences begin to emerge in the processing of faces; for example, English children tend to look at their mouths longer than Japanese children, conversely the latter look at the eyes of others longer than the former. Despite these differences, the behavioral patterns of responses to direct gazes or responses to gazes turned elsewhere are still the same in both cultures at that age (Senju et al., 2013).

2.6

Innate and Acquired Skills

Of particular interest for our line of research is the idea that Mark Johnson (2005) has been trying to demonstrate for some years. According to this author, the subcortical pathways of perception of the gaze of newborns perform two functions: (1) they identify the presence of faces and (2) they determine - through preferential projections - which neocortical areas will be associated with the social brain network. According to this hypothesis, in other words, the subcortical areas that in newborns respond to the vision of faces increase the activity of the cortical areas which, even at birth, receive little stimulation from the neocortical visual areas since these do not yet work very well. This increase in activity causes the social brain network to develop. In 1991, together with John Morton, the same author had developed a model that involved two distinct processes for processing the faces of newborns. The first of these two was called CONSPEC and would be the one that drives the innate preference for stimuli that resemble faces, CONSPEC processes the eye / mouth pattern in a very simple way and is subcortical. The CONSPEC is joined by CONLERN, but only after 2 months of life. The latter retains in memory the information needed to identify the faces of conspecifics and is cortical. CONLERN is not a stimulus-specific learning modality and children are learning better and better to identify the faces of conspecifics simply because they look longer in their faces than they look at other stimuli; naturally they devote more attention to faces thanks to the action of CONSPEC. After the first month of life, CONSPEC takes a secondary role as cortical structures begin to have greater control over behavior. About the fifth month of life, the CONLERN allows the baby to recognize faces even without the presence of the minimum pattern.

References Almasi, R. C., & Behrmann, M. (2021). Subcortical regions of the human visual system do not process faces holistically. Brain and Cognition, 151, 105726. Atkinson, J. (2008). The developing visual brain. Oxford University Press.

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Baron-Cohen, S., Campbell, R., Karmiloff-Smith, A., Grant, J., & Walker, J. (1995). Are children with autism blind to the mentalistic significance of the eyes? British Journal of Developmental Psychology, 13(4), 379–398. Batki, A., Baron-Cohen, S., Wheelwright, S., Connellan, J., & Ahluwalia, J. (2000). Is there an innate gaze module? Evidence from human neonates. Infant Behavior and Development, 23(2), 223–229. Belini, A. E. G., & Fernandes, F. D. M. (2010). The development of looking behavior and eye-contact in breast feeding children aged between 0 and 4 months. Revista Brasileira de Saúde Materno Infantil, 10, 85–93. Born, A. P., Rostrup, E., Miranda, M. J., Larsson, H. B. W., & Lou, H. C. (2002). Visual cortex reactivity in sedated children examined with perfusion MRI (FAIR). Magnetic Resonance Imaging, 20(2), 199–205. Bronson, G. (1974). The postnatal growth of visual capacity. Child Development, 873–890. Brooks, R., & Meltzoff, A. N. (2002). The importance of eyes: How infants interpret adult looking behavior. Developmental Psychology, 38(6), 958. Brooks, R., & Meltzoff, A. N. (2005). The development of gaze following and its relation to language. Developmental Science, 8(6), 535–543. Buiatti, M., Di Giorgio, E., Piazza, M., Polloni, C., Menna, G., Taddei, F., et al. (2019). Cortical route for facelike pattern processing in human newborns. Proceedings of the National Academy of Sciences, 116(10), 4625–4630. Dubowitz, L. M. S., De Vries, L., Mushin, J., & Arden, G. B. (1986). Visual function in the newborn infant: Is it cortically mediated? The Lancet, 327(8490), 1139–1141. Einav, S., & Hood, B. M. (2008). Tell-tale eyes: children’s attribution of gaze aversion as a lying cue. Developmental Psychology, 44(6), 1655. Farroni, T., Csibra, G., Simion, F., & Johnson, M. H. (2002). Eye contact detection in humans from birth. Proceedings of the National Academy of Sciences, 99(14), 9602–9605. Farroni, T., Johnson, M. H., Brockbank, M., & Simion, F. (2000). Infants’ use of gaze direction to cue attention: The importance of perceived motion. Visual Cognition, 7(6), 705–718. Farroni, T., Johnson, M. H., & Csibra, G. (2004). Mechanisms of eye gaze perception during infancy. Journal of Cognitive Neuroscience, 16(8), 1320–1326. Farroni, T., Johnson, M. H., Menon, E., Zulian, L., Faraguna, D., & Csibra, G. (2005). Newborns’ preference for face-relevant stimuli: Effects of contrast polarity. Proceedings of the National Academy of Sciences, 102(47), 17245–17250. Farroni, T., Menon, E., & Johnson, M. H. (2006). Factors influencing newborns’ preference for faces with eye contact. Journal of Experimental Child Psychology, 95(4), 298–308. Freire, A., Eskritt, M., & Lee, K. (2004). Are eyes windows to a deceiver’s soul? Children’s use of another’s eye gaze cues in a deceptive situation. Developmental Psychology, 40(6), 1093. Frischen, A., Bayliss, A. P., & Tipper, S. P. (2007). Gaze cueing of attention: Visual attention, social cognition, and individual differences. Psychological Bulletin, 133(4), 694. Geldart, S., Maurer, D., & Carney, K. (1999). Effects of eye size on adults’ aesthetic ratings of faces and 5-month-olds’ looking times. Perception, 28, 361–374. Goren, C. C., Sarty, M., & Wu, P. Y. (1975). Visual following and pattern discrimination of facelike stimuli by newborn infants. Pediatrics, 56(4), 544–549. Hood, B. M., Willen, J. D., & Driver, J. (1998). Adult’s eyes trigger shifts of visual attention in human infants. Psychological Science, 9(2), 131–134. Johnson, M. H. (1990). Cortical maturation and the development of visual attention in early infancy. Journal of Cognitive Neuroscience, 2(2), 81–95. Johnson, M. H. (2005). Subcortical face processing. Nature Reviews Neuroscience, 6(10), 766–774. Johnson, M. H., Dziurawiec, S., Ellis, H., & Morton, J. (1991). Newborns’ preferential tracking of face-like stimuli and its subsequent decline. Cognition, 40(1–2), 1–19. Jones, W., & Klin, A. (2013). Attention to eyes is present but in decline in 2–6-month-old infants later diagnosed with autism. Nature, 504(7480), 427–431.

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Kim, S., Fonagy, P., Koos, O., Dorsett, K., & Strathearn, L. (2014). Maternal oxytocin response predicts mother-to-infant gaze. Brain Research, 1580, 133–142. Kimura, I., Kubota, M., Hirose, H., Yumoto, M., & Sakakihara, Y. (2004). Children are sensitive to averted eyes at the earliest stage of gaze processing. Neuroreport, 15(8), 1345–1348. Kobayashi, H., & Hashiya, K. (2011). The gaze that grooms: contribution of social factors to the evolution of primate eye morphology. Evolution and Human Behavior, 32(3), 157–165. Kylliäinen, A., Braeutigam, S., Hietanen, J. K., Swithenby, S. J., & Bailey, A. J. (2006). Face and gaze processing in normally developing children: A magnetoencephalographic study. European Journal of Neuroscience, 23(3), 801–810. Lamberg, B. R. (1981). Eye opening of the newborn at and up to 20 minutes after birth. Journal of Advanced Nursing, 6(6), 455–459. Mareschal, I., Otsuka, Y., Clifford, C. W., & Mareschal, D. (2016). “Are you looking at me?” how children’s gaze judgments improve with age. Developmental Psychology, 52(5), 695. Maurer, D., & Young, R. E. (1983). Newborn’s following of natural and distorted arrangements of facial features. Infant Behavior and Development, 6(1), 127–131. Mercuri, E., Atkinson, J., Braddick, O., Anker, S., Cowan, F., Rutherford, M., et al. (1997). Basal ganglia damage and impaired visual function in the newborn infant. Archives of Disease in Childhood-Fetal and Neonatal Edition, 77(2), F111–F114. Moll, H., & Tomasello, M. (2004). 12-and 18-month-old infants follow gaze to spaces behind barriers. Developmental Science, 7(1), F1–F9. Ochs, E., & Schieffelin, B. B. (2009). Language acquisition and socialization: Three developmental stories and their implications. v: Duranti, A., LeVine, R., A., ur., Linguistic anthropology, Oxford, Blackwell Publishing. Parise, E., Reid, V. M., Stets, M., & Striano, T. (2008). Direct eye contact influences the neural processing of objects in 5-month-old infants. Social Neuroscience, 3(2), 141–150. Pascalis, O., de Martin de Viviés, X., Anzures, G., Quinn, P. C., Slater, A. M., Tanaka, J. W., & Lee, K. (2011). Development of face processing. Wiley Interdisciplinary Reviews: Cognitive Science, 2(6), 666–675. Ramenghi, L. A., Ricci, D., Mercuri, E., Groppo, M., De Carli, A., Ometto, A., et al. (2010). Visual performance and brain structures in the developing brain of pre-term infants. Early Human Development, 86(1), 73–75. Reid, V. M., Dunn, K., Young, R. J., Amu, J., Donovan, T., & Reissland, N. (2017). The human fetus preferentially engages with face-like visual stimuli. Current Biology, 27(12), 1825–1828. Ricci, D., Anker, S., Cowan, F., Pane, M., Gallini, F., Luciano, R., et al. (2006). Thalamic atrophy in infants with PVL and cerebral visual impairment. Early Human Development, 82(9), 591–595. Rigato, S., Menon, E., Johnson, M. H., Faraguna, D., & Farroni, T. (2011). Direct gaze may modulate face recognition in newborns. Infant and Child Development, 20(1), 20–34. Salva, O. R., Farroni, T., Regolin, L., Vallortigara, G., & Johnson, M. H. (2011). The evolution of social orienting: Evidence from chicks (Gallus gallus) and human newborns. PLoS One, 6(4), e18802. Senju, A., & Csibra, G. (2008). Gaze following in human infants depends on communicative signals. Current Biology, 18(9), 668–671. Senju, A., & Johnson, M. H. (2009). The eye contact effect: mechanisms and development. Trends in Cognitive Sciences, 13(3), 127–134. Senju, A., Tojo, Y., Dairoku, H., & Hasegawa, T. (2004). Reflexive orienting in response to eye gaze and an arrow in children with and without autism. Journal of Child Psychology and Psychiatry, 45(3), 445–458. Senju, A., Vernetti, A., Kikuchi, Y., Akechi, H., & Hasegawa, T. (2013). Cultural modulation of face and gaze scanning in young children. PLoS One, 8(8), e74017. Simion, F., Valenza, E., Umilta, C., & Barba, B. D. (1998). Preferential orienting to faces in newborns: A temporal - nasal asymmetry. Journal of Experimental Psychology: Human Perception and Performance, 24(5), 1399.

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Symons, L. A., Hains, S. M., & Muir, D. W. (1998). Look at me: Five-month-old infants’ sensitivity to very small deviations in eye-gaze during social interactions. Infant Behavior and Development, 21(3), 531–536. Valenza, E., Simion, F., Cassia, V. M., & Umiltà, C. (1996). Face preference at birth. Journal of Experimental Psychology: Human Perception and Performance, 22(4), 892. Woo, B. M., & Schaller, M. (2020). “Parental” responses to human infants (and puppy dogs): Evidence that the perception of eyes is especially influential, but eye contact is not. PLoS One, 15(5), e0232059.

Chapter 3

Emotional Tears: A Human Uniqueness

“Then something began to hurt Mowgli inside him, as he had never been hurt in his life before, and he caught his breath and sobbed, and the tears ran down his face. ‘What is it? What is it?’ he said. ‘I do not wish to leave the jungle, and I do not know what this is. Am I dying, Bagheera?’ ‘No, Little Brother. Those are only tears such as men use,’ said Bagheera. ‘Now I know thou art a man, and a man’s cub no longer. The Jungle is shut indeed to thee henceforward. Let them fall, Mowgli. They are only tears.” Jungle Books Kipling, Rudyard “I am blind, I am blind, he repeated in despair as they helped him to get out of the car, and the tears welling up made those eyes which he claimed were dead, shine even more”. Blindness Saramago, Jose

3.1

The Cognitive Role of Human Tears

You are a man, Mowgli. You are a man and it is not your erect position or your almost hairless body that proves it. It is not even the language, because in the world invented by Kipling also the other animals speak. The only reliable sign of your humanity are tears, dear Mowgli. Yes Mowgli, only humans shed tears, so if you shed them, you are certainly one of us. Tears have a very precise function: to lubricate the animal’s eye, keeping it clean and removing the possible causes of inflammation. When an animal closes and reopens its eyes, it promotes the exchange of tears and therefore the lubrication and cleaning of the eye. However, the chemical composition of the tear differs from animal to animal; in primates it is characterized by a higher concentration of lactoferrin, a bactericidal protein (Trimble, 2012). Probably not by chance, the © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Pennisi, Gazes, Words, and Silences in Pragmatics, Perspectives in Pragmatics, Philosophy & Psychology 36, https://doi.org/10.1007/978-3-031-42571-4_3

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3 Emotional Tears: A Human Uniqueness

primate with the most similar tear composition to humans is the chimpanzee (ibid; Bodelier et al., 1993). In humans, tears also have an emotional function and the chemical composition of reflex tears and emotional tears is different (Liang et al., 2022). We know surprisingly little about the neurobiology of crying in humans (see Bylsma et al., 2019 for an accurate examination); among the few certain data, however, there is a very significant one: children who are born without telencephalon (a structure that will evolve in the cerebral hemispheres) due to very serious congenital malformations are still able to cry, and therefore in the newborn the telencephalon is not indispensable for the manifestation of such behavior. This perspective is called ‘the brainstem model’ and assumes that in human infants the rostral brain structures relative to the brainstem are not indispensable for crying (Newman, 2007). However, the reference in this case is to reflex weeping, the one that unites all mammals, not tearful weeping. Unfortunately, anencephalic children usually survive for a few days at most, so they do not develop the tearful weeping that instead appears between the first and second month of life (Murube et al., 1999). In contrast, crying in adults is associated with increased activity of both cortical and subcortical areas (Bylsma et al., 2019). The physiological function of the tear is common to all terrestrial vertebrates, but what is interesting to reflect on from a philosophical point of view is the cognitive and emotional function of the tear. The following pages, through an analysis of the data and theories elaborated so far on the subject, will try to demonstrate that tears, when they are an expression of the emotional life of man, assume a cognitive function both for the subject who cries and for the one who observes the one who weeps. In fact, they are a sign of the reliability of the feeling associated with tears. It is no coincidence that it is the speaking species that has invested energy in such an expensive behavior only to indicate the reliability of the sentiment expressed: man can lie with language (to himself and to others), therefore an evident signal of distinction between truth and falsehood (towards others or towards oneself) in terms of feelings, it greatly contributes to orienting the reaction behavior of whoever receives the signal (sometimes even just the transmitter itself).

3.2

Tears in Other Animals

It seems to be no reference to emotional tearful weeping in amphibians or birds in the literature. In the behavior of reptiles, however, some episodes of physiological tearing have over time been confused with cases of emotional expression. For example, some anecdotal stories of emotional crying in turtles can actually be explained in light of the fact that the tortoise’s ocular secretion tends to submerge the eyelid, giving the impression that the animal is crying (Murube, 2009). The other reptile famous for its tears is the crocodile. It is commonly said that those who repent after committing something that then go back to doing shortly afterwards make

3.2

Tears in Other Animals

19

“crocodile tears”. The story of the saying is exhaustively told by Vingerhoets (2013: 16–19); however, the saying is not completely without empirical foundation. In fact, it happens to observe tears in the eyes of crocodiles who are eating or who have just finished eating. Who - among the readers - is thinking about that time that he made “crocodile tears” after devouring a box of chocolates - before starting to feel a certain affinity between himself and these terrible predators - should know that, it is true that these secretions that seem tears depart from the nasolacrimal canal, but they never wet the inside of the eye; on the contrary they reach the oral cavity, and this last passage suggests that actually tears have the function of lubricating the bolus and that they are not an expression of emotion for the goodness of the meal or repentance for the excess calories just swallowed (Murube, 2009). In mammals, on the other hand, it is more difficult to clearly establish the presence or absence of emotional crying. Many anecdotal accounts report emotional tearful cries in dogs and in some cases even in wolves, but none of these have ever been supported by film material or data collection with scientific methodology. Always anecdotal observations from various sources report that seals tend to tear abundantly from the eyes when they are agitated; otters if intentionally deprived of their cubs cry with tears (ibid). In The Expression of Emotions in Man and Animals Charles Darwin (1870) devoted himself to the explicit search for non-human animals that cry with tears. The research of him among the primates did not give good results; those on elephants were more fertile. However, he refers to the anecdotal stories reported by Sir E. Tennent in Ceylon (1859) in which it is told of Indian elephants that during their capture by men fall down and fill their eyes with tears. Darwin himself, however, although he claims to believe these tales, is forced to admit that the indigenous hunters assure that he has never seen an elephant cry and that the African elephant, subjected to the same treatment as the Indian ones, had not paid any tear. According to Murube (2009), the frequent anecdotal inconsistencies on the alleged crying of elephants can be explained by observing the phylogenetic history of the elephant’s tear duct that has led them to a conformation that favors abundant reflex tearing that makes it appear that the animal is crying. Dian Fossey (1983), in her Gorillas in the mist actually reports of a gorilla who on a particular occasion sheds tears while experiencing a negative emotion. Fossey herself, however, specifically points out that this is the only time she has ever seen a gorilla cry. In summary, therefore, tearful crying linked to particular psycho-emotional states is safe only in the human being. In some animals, anecdotal reports suggest that the phenomenon could also be present in some other animal species, however these reports must be carefully considered: the particular physiological conformation of the tear ducts of the animals in question may have induced the observers of these “cries animals” in error; maybe the animal had a tear reflected in a moment of emotional stress and the observer misunderstood the reasons for the manifest behavior. No data obtained with a scientific and final methodology has ever confirmed these sporadic stories. In any case, even when the latter were confirmed, what emerges from the literature is that, even in some cases in the rest of the animal world,

20

3 Emotional Tears: A Human Uniqueness

emotional tearful crying occurred, it is not the norm and it is not as frequent as in humans.

3.3

Tears as Individual Relief

But why does the human being produce tears as a result of particular emotional states? Since emotional tears are a human peculiarity, they have naturally not failed to arouse the curiosity of many scholars. Below we will discuss some of the most influential and well-known theories in this area. The most effective classification that can be made of them is that which distinguishes the social function from that of individual relief. Let’s start with a discussion of the latter. According to Darwin (1870), crying is an effect of compression of the lacrimal gland. The human child, like other mammalian babies, emits loud cries to ask for the help of their parents; these cries (partly a relief in themselves) cause the blood vessels of the eyes to become engorged. At this point the eyes of the muscles surrounding the eyes contract to protect them. The joint action of blood vessel dilation and muscle contraction would cause the tear reflex. Growing this reflex is associated with pain even without this going through the pressure of the tear ducts. Although Darwin recognizes the social value of the recall signal, he nonetheless insists on its cathartic function: “And by as much as the weeping is more violent or hysterical, by so much will the relief be greater,—on the same principle that the writhing of the whole body, the grinding of the teeth, and the uttering of piercing shrieks, all give relief under an agony of pain (Darwin, 1870:185)”. The anatomical and physiological features of Darwin’s theory are not supported by scientific evidence today (Murube et al., 1999). The idea that the emission of tears is associated with an attenuation of physical suffering is repeatedly reiterated by Darwin, but in fact never strongly argued. In Studies on Hysteria Freud and Breuer actually argue that reactions to trauma only become cathartic if complete and crying would be part of these reactions. But despite some sporadic references to patients crying, their work does not have a complete theory on the role of crying in overcoming trauma or in maintaining mental health in general. Although a cathartic theory has not found systematic support in the scientific literature, recently on this concept Gračanin et al. (2014) argued that crying actually has a homeostatic regulating function that normally calms the crying person, helping the crying person regulate emotions. This process, however, can also be completely neutralized by some external factors, for example the social embarrassment that can be experienced in public in contexts where it is not normally accepted, such as the professional one. The authors speak of crying as a self-soothing phenomenon: “a form of emotional regulation, which includes intrinsic and extrinsic processes involved in monitoring, evaluating and modifying emotional reactions” (ibid.). This theory could find partial confirmation in the fact that the innervation of the lacrimal glands is both sympathetic and parasympathetic, but the parasympathetic system predominates both from

3.4

Social Theories on Emotional Tears

21

an anatomical and functional point of view (Dartt, 2009; Kardon 2005). We recall here that the parasympathetic nervous system is what normally pushes towards a neuropsychological relaxation of the individual, while the sympathetic system tends to the psychological activation of the individual. Their alternation, with a predominance of the activation of the parasympathetic system is in fact consistent with the idea that tears promote emotional regulation. In particular, it is assumed that the onset of crying is associated with an increase in sympathetic activity, while the parasympathetic system seems to be active for the duration of the crying (Bylsma et al., 2019). There were also attempts to explain the presence of the human tear in strictly physiological terms. For example, Montagu (1960) argued that they had the indispensable role of keeping the mucous membrane moist. This type of explanation, however, is often easily discredited by the observation that tears, as we said in §1.5, start only from the first month of the child’s life, or at least between 4 and 8 weeks of life (Murube et al., 1999). As well as other perspectives on the potential role of cleansing tears from toxic substances produced by emotional stress have been abandoned following the finding that no toxic substances were found in the tears (ibid).

3.4

Social Theories on Emotional Tears

Let’s now look at some of the most convincing theories on the social origin of emotional tears. Let’s start with the idea of the German ethologist Frans Roes (1989), who starts from the observation that in many animal species, adults who find themselves in a situation where they completely lack social control, imitate the helplessness of children, thus requiring the mobilization of prosocial behaviors by those around them at that moment. For example, older chimpanzees begging for food from other group members use the same facial expression as young chimpanzees who are separated from their mother. Therefore, for Roes, the crying of adults would be a manifestation of this habit of imitating children that occurs in adults who need help from others. Although the theory has elements of interest, actually it only circumvents the question, which at this point could be posed in these other terms: why do children (and therefore consequently also adults) shed emotional tears? Several other theories, on the other hand, have focused on the idea that tears are a rather reliable sign of vulnerability. Murube et al. (1999) proposed what was baptized with the expression theory of the symbol of suffering. According to these scholars, tearing has become a symbol of sadness for men because it is associated with certain eye problems and pains such as acute conjunctivitis or ulcers. Just as showing teeth has become a symbol of attack, so showing tearing has become a symbol of suffering. This theory has also attracted the attention of those involved in nerve grow factor (NGF), the protein discovered by Rita Levi Montalcini involved in the development

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3 Emotional Tears: A Human Uniqueness

of the vertebrate nervous system. Indeed, the presence of NGF has been found in human tears (Nguyen et al., 1997; Park et al., 2008). The concentration of NGF in tears is also very high after a corneal injury (Woo et al., 2005). These data led Robert Provine, a Montalcini student, to hypothesize that emotional tears are a sort of side effect of functional tears: in individuals with large tearing due to an eye problem, copious tears had the effect of mobilizing prosocial behaviors of the group. This symptom eventually became a sign of emotional or physical distress through a process of ritualization (Provine, 2011). In reality, the awareness of the presence of NGF does not add much to our speculations on tears, but it is possible that in the future this figure will become an important link in the historical reconstruction of the evolution of emotional tears. Walter Chips attempts to provide an explanation to this phenomenon through the Handicap Principle by Zahavi and Zahavi (1999) by arguing that the very high cost of crying with tears is probably balanced by the reliability of the signal: with tears we make clearer not only the emotion we are feeling, but even the reliability of our communication; in fact, the muscles responsible for crying in men are impossible to control during an emotionally intense state and also the presence of tears makes emotional expressions unmistakable (Walter, 2006). An interesting extension of this perspective comes to us from the words of Vingerhoets (2013) who argues that tears, together with redness in the face, indisputably signal fulfillment and pleading to other members, leading the latter to greater trust and social connection. A study of Spanish participants showed that they were inclined to find people who cried more trustworthy, kinder, and more prone to remorse after a social transgression than people who did not (Picó et al., 2020). We can also add some observations to these theories. There is a bitter debate on the idea that the smell of female tears induces to allay sexual arousal in men (Gelstein et al., 2011; Gračanin et al., 2017a, 2017b; Sobel, 2017). For the purposes of this discussion, however, it really matters little whether they also act chemically, in reality the acoustic and visual signals emitted by human beings during crying seem more than sufficient to justify the moderate power it has to generate social cohesion. Chemical or not, a woman who is not available for mating at that moment can maintain cohesion with the man through tears. Vingerhoets (2013) poetically describes tears as the “weapons of the weak”.

3.5

Weapons of the Weak

Who has never been defeated by a child’s tear? Perhaps seen in the advertisement of an ONLUS that asks for monthly donations for the defense of human rights; or on the face of his son, when after the umpteenth prank of anger he finally decides to give up and ask for forgiveness with a liberating cry. In this paragraph we will try to support the primarily social function of the tear. Such a statement may seem paradoxical after recognizing the existence of a liberating feeling associated with crying, but in fact it is not exactly the case.

3.5

Weapons of the Weak

23

Of all the theories we have just seen as to why emotional tears evolved in the human race, none have yet gained the full agreement of the scientific community. This of course is linked to the fact that all these theories have a predominantly speculative nature. The goal is to understand why man appears to be the only animal that sheds tears to accompany emotional states. Primates have behaviors (howling, screeching) that can be considered crying, but they do not have emotional tears and even if one day someone will proves, in the wake of Fossey, that animals do, certainly these tears will not have the same pervasive presence that they have in humans, especially during the first months of life. As Provine (2011) rightly pointed out with reference to the Handicap Principle (Zahavi & Zahavi, 1999), crying with tears is very expensive for the infant. The infant loses precious liquids and calories, which become a waste of liquids and calories even for the mother who will have to replenish them with breastfeeding. If such behavior has been carried out despite the cost it has, evidently it must be associated with a strong immediate advantage. In the absence of genetic theories on the need to develop this particular functioning mechanism, we are forced to hypothesize that tears have a function that can be immediately connected to the fitness of the species. Individual advantage theories have little (usually no) scientific support. Only the idea of Gračanin et al. (2014) cites valid empirical data. The point is that they are all focused on the idea that crying, in some way and under some circumstances, makes the individual feel better. But in fact, it is not here to deny that sometimes crying makes people feel better or stop some unwanted emotional states. However, thinking that crying has evolved because it has the task of putting an end to unwanted emotional states is like thinking that the act of eating has evolved to stop hunger pangs. Certainly, when we have to cry, we experience prodromal sensations to weeping, which cease with it; but they are simply part of the process, they do not cause it. What causes it then? This is caused by the need to communicate to those around us that we have given up control over the situation; that we need the support of the group and that we are asking for it in a non-aggressive but submissive way. Often, we are even asking against our will and that the sincerity of our request is final because the tear testifies to its reliability. Several objections can be raised to this idea, each of them will be analyzed in the next pages. Objection (i): Many individuals cry alone in a room and get no help from others. Objection (ii): culture can inhibit or accentuate the tendency to cry. Objection (iii): we do not cry only in times of difficulty but also for joy; by emotion in front of a film; out of nostalgia; after an orgasm.

3.5.1

A Way for the Linguistic Thinking

If tears have - as we are trying to prove - a social origin, it is necessary to explain why it often happens that human beings cry in solitude and why this can sometimes make them feel relieved. Indeed, probably all human beings have cried in solitude at least

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3 Emotional Tears: A Human Uniqueness

once in their life. But this observation is not harmful to the theory of the social origin of tears because language makes the ego not only the active component of the mind that produces the message, but also one of its recipients at the same time. The existence of inner dialogue, possible only thanks to language, makes the human being simultaneously the creator and recipient of his own thoughts. Because in the passages from one form of thought to another (from silent to oral thought and vice versa), different forms of meaning are generated which will correspond to different behaviors. It is no coincidence that to all human beings - sooner or later happen to say something in public that they did not even know they had ever thought. The audible articulatory act objectified a thought that had condensed, in the solitude of one’s mind, into a form that had different consequences on behavior. Subject was not aware of it. But this form of inner dialogue had evidently become inadequate or insufficient for the treatment of that thought, which now instead needed to be objectified through articulation. Part of bodily feeling does not reach conscious thought; but everything that reaches conscious thought passes through language and is profoundly altered by it. Very intense emotions cause a strong physiological disruption in the body and language, through its filter, can contribute to restoring balance. Our nature as talking animals with self-awareness associates crying in solitude with a social component in a certain sense: when we cry in solitude we become our own audience, or through the tearful weeping our body perceives the awareness of reliability. The emotion associated with tears; the conscience will have to analyze this emotion because the tear has attested its importance and authenticity: now even linguistic thought becomes responsible for it. In a certain sense, the lonely tear ensures that the emotion associated with it, if it was not already placed on a conscious level, is at least so after the cry. After the cry, it will necessarily be grasped by the conscious self and treated by the subject’s inner dialogue in all its intensity and authenticity. A person can be hungry without being fully aware of it, and this feeling can manifest itself through a form of nervousness. Similarly, a person can be sad without fully grasping the depth of her sadness, but that can no longer happen if the tears have reached her eyes. Likewise, whoever surrounds a subject can perceive, for example, its sadness; but it will be lawful to ignore this feeling until it is sealed and made reliable through the tear. After the tear, however, the subject who cries knows that the others know that he is suffering and any indifference of his audience will be considered a very serious form of social isolation. The physical presence of a signal that manifests itself in the sunlight, under the eyes of those who emit it and those around them, will oblige the recipients (and the subject that emits it must also be included among the recipients) to consider it and to act consequentially.

3.5.2

A Collateral Effect

In fact, the issue is macroscopic and requires the acceptance of many assumptions that not all readers will be willing to concede. However, it will not be possible to

3.5

Weapons of the Weak

25

deepen the question further as this would lead to a dispersion of the discourse too far from the starting point. An attempt will therefore be made to respond to objection one also in another way, acceptable even for those who do not consider valid the idea that language makes the human being both the sender and the receiver of his thoughts. In fact, even if the reader does not want to accept the description proposed here of linguistic thought as a form of thought in which the body makes the subject a recipient of its own messages, the theory of the social function of tears would in any case not be invalidated by the human habit of lonely cries. To explain why, let us return once again to the example of hunger. Normally living beings eat to feed themselves and it is for this purpose that, in order to eat, animals fearlessly face the most frightening dangers. In humans the act of eating has evolved, as in other living beings, for the nourishment of the individual, however this behavior also manifests itself for other reasons, especially when it does not involve great risks or even just the fatigue of having to go up to the supermarket: we eat out of hunger, we eat for gluttony, we eat out of boredom, we eat for sharing, we eat because we feel alone, we eat out of anxiety, etc. ... This is because eating is such an important survival mechanism that it is somewhat redundant in the brain (Guyenet, 2017). This means that the individual often eats even if he does not need to feed himself. In many cases, especially in the most highly industrialized societies, this disconnection between the manifestation of behavior and the function for which it occurs becomes even a problem for the individual: the high availability of food and the ability to eat easily are transformed often in eating disorders that lead to overweight and obesity. But all this does not change a central observation for those who study man by accepting the Darwinian perspective: the individual who eats feeds and therefore survives and reproduces. Let’s go back to lonely cries. Denying the existence of lonely crying would be like denying that many people eat out of anxiety and that they do it even if they don’t need to feed themselves. But crying in solitude is possible because crying has evolved, and crying in turn has evolved because it facilitates intraspecific communication. In some cases, not always (Gračanin et al., 2014), after a lonely cry the individual feels better; in the same way, after eating out of anxiety, the individual also fed. But this too is a side effect of the very function for which crying has evolved; that is the function of signaling to others our surrender, our genuine need for help or in any case that our signal is reliable.

3.5.3

Culture and Tears

Cryng is not culture-specific, it is universal among humans: it is present in all cultures and not only in children but also in adults; however, all cultures more or less explicitly regulate the acceptability of such behavior. For example, in some African cultures, boys are encouraged to cry over physical pain in everyday life, but are prohibited from crying during their own circumcision (Mhlahlo 2009; for a review of the literature on the social regulation of crying, see Gračanin et al. 2018).

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Emotional Tears: A Human Uniqueness

That culture exercises a very strong power in influencing the manifestation of crying is evident even only in our daily experience. We are easily able to recognize contexts in which crying would be socially inappropriate and unappreciated behavior. In these contexts, we strive to avoid crying and in most cases we succeed. This of course can lead us to believe that crying is ultimately controllable and consequently perhaps a not so reliable signal. To answer this possible objection, it is first of all necessary to specify that when a subject manages to suppress crying and push it back in, he is normally acting on the emotion associated with it and not on the crying itself. That is, if during a clash with a work colleague, or worse with one of our superiors, we feel the so-called lump in our throat and push it back down to avoid crying, we are intentionally recall a certain type of meaning), generally it is an index that means that it is unintional, reliable and even almost inevitable in some cases. Like a foot crossing the sand leaves footprints (which can be left intentionally, but normally are not deliberately created in order to be interpreted) by virtue of the inevitable physical causality relationship between the passage of the sender and the impression of the material support; in the same way the emotional tears are generated by virtue of a physical causality between the emotional experience of the sender and the necessary bodily expression of the same. In fact, although, as we have said, the exact neurobiology of the emotional tear is still largely unknown, I believe that it derives from chemical and neurophysiological mechanisms which inevitably force the subject to express emotion in this way when it is very strong. I’m not even sure it’s wise to maintain this philosophical dichotomy between the experience of emotion and the expression of emotion; in fact, to avoid useless philosophical duplication, one could perhaps even say that the emotion is the expression and the tear is an integral part of the expression of some strong emotions (but on this I leave the question open because it would shift the discussion onto a which goes beyond the ultimate goals of this discussion). Of course, this perspective at present still has a purely speculative nature and needs further scientific confirmation. But the fact that the remote possibility to pretend emotional tears exists does not invalidate the central point of view that I am trying to express here: the fiction of the emotional tear is so difficult and risky that it is rarely used. Movies are of course an exception to this rule; just as it is possible that some people exercise the ability to self-generate the tear of the eye and associate it with an auto-suggestion towards sadness so strong that they manage to seem authentic even when they shamelessly pretend. However, one cannot achieve the exercise of these competences without long premeditations and exercises; which makes the danger of genuinely believing in actually fake tears a very unlikely danger in principle. For this reason, when we witness emotional tears being shed that appear genuine to us, we tend to rely on this feeling much more than we would with words that appear genuine to us.

3.5

Weapons of the Weak

3.5.4

27

Authenticity Does Not Necessarily Mean Others’ Help

What is social about being moved to have reached the top of a mountain whose climbing had always remained on one’s personal wish list? What is social about having found a forgotten toy of your child, now that he is 40 years old? The social value of tears and their power to foster social connection could be questioned by the existence of tears not only related to sadness and need for help, but also related to joy, emotion or other positive events. Several scholars have tried to analyze and isolate the occasions that most easily elicit crying. Vingerhoets (2013) offered an interesting review, in which the potential triggers of tears were polarized as related to two feelings: a sense of helplessness and a need for help versus attachment and social connection. On the basis of these fundamental polarities of the human psyche he then found mutually complementary triggers; its classification is reported in Table 3.1. Therefore according to Vingerhoets (2013) these social situations in which crying occurs more frequently have in common either the sense of helplessness and need for help or the perception of a sense of attachment and social connection; these two occurrences are the side of the same coin and make evident the social role of emotional tears. Gračanin et al. (2018) go one step further, classifying not only the potential triggers of crying, but also classifying them according to the difference in occurrence (i.e. childhood, adulthood, ritual situations) and associating them with the reactions of others. However, both efforts of these scholars focus the center of the question on the social role of tears. Let’s start with the most controversial example, as seen in Table 3.2, Gračanin et al. (2018) report that, in case of poor physical health, the baby’s crying could even become a sign for the parents of the need to divest him of parental care, or, to put it in more crude terms, to abandon him to his sad destiny. Table 3.1 Causes of tears. Vingerhoets (2013) Helplessness and incapacity to adequate functioning death, loss divorce, relationship breakdown separation conflict loneliness defeat powerlessness and/or failure emotional suffering old, discarded, worn out sun, egoism, world is bad tiny, vulnerable, helpless physical pain seeing others suffering

Attachment and social connectedness childbirth wedding reunion harmony social bonding victory extraordinary performance happiness young, vulnerable, with potential justice, altruism, world is good overwhelming, mighty, awesome orgasm seeing others feeling very happy

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3 Emotional Tears: A Human Uniqueness

Table 3.2 Causes and social reactions to tears. Gračanin et al. (2018) Antecendents Infant crying

Physical/mental discomfort/ separation

Poor physical health Adult crying

Distress Separation Sentimental/moral issues Confession, supplication, guilt

Ritual/Common weeping

Disasters Penitentiary festivals

Preparation for war Bereavement

Greeting rituals

What does it convey? Need for help

Low survival chances Need for help Need for help and procimity Compliance with proper social and moral values Need for forgiveness, submission Need for help, to belong, submission Need for forgiveness, submission Display of unity Compliance with proper social and moral values Absence of hostility, friendly intentions

Reaction of others Caregiving, comfort, physical proximity; reduction in aggression (of strangers and caregivers) Reduction in investment Comfort, advice, help Comfort, bonding Bonding, appeasement

Help, forgiveness (from deities) Appeasement (of higher powers/deities) Help (from deities)

Bonding Bonding, appeasement (of spirits of deceased) Bonding

Clearly, in imagining this scenario, the authors are not thinking of a parent from the rich world who contacts the most famous, important and expensive doctors to have even a thousandth of hope of saving their child, but of an evolutionistically or anthropologically more large in which itinerant parents who live in adverse ecological situations must evaluate how to invest their resources, whether to feed other siblings, or to father siblings more likely to be healthy. According to a fairly wellknown model in the literature, known as the super-baby hypothesis, a vigorous crying in the infant would induce parents to invest more in parental care for him and thus inhibit them from making other siblings, at least immediately (Lummaa et al., 1998); a weak cry, therefore, would be configured as a disincentive to invest further in him. Infanticide is present in many species of primates, but it is usually perpetrated by males who are not the fathers of the puppy and the scientific community almost unanimously believes that this phenomenon, as well as being rare, is linked to the fact that the killer will be more likely to mate with the mother of the killed puppy because after the death of the puppy she will sooner be fertile and available for

3.5

Weapons of the Weak

29

mating (Zhang et al., 2012). Various ethnographic sources have documented similar behavior in humans as well (for a review see Alexander 1974). But in humans, infanticide also occurs for other reasons and among these a physical deficit of the puppy is one of the possible causes (Hrdy 1979). Famous in the Western collective imagination is the case of Sparta, where - according to Plutarch - newborns who appeared to be physically weak were thrown off a cliff near Taygetos (Plutarch, Licurgo XVI). Recent studies have shown that it is very difficult for the practice to be institutionalized as instead emerges from the words of Plutarch; however it is likely that this practice was widespread but practiced with shame (Sneed 2021). And in any case beyond Greece, infanticide is unfortunately also systematically perpetrated all over the world for the most varied reasons (cf. i.e. Balikci, 1967). If then, in a broader perspective, we consider the problem from the point of view of the orientation of birth control and consider abortion (carried out among other things often due to fetal diseases) together with cases of infanticide, it is understandable that this is even an institutionalized practice in many countries. Some primate pups have shown attempts to defend themselves from these mechanisms. For example, a very recent study of white-faced capuchins revealed that puppies between 8 and 23 months make particular sounds when they are faced with a dominant male in the group who is not their father (and therefore could potentially kill them). Researchers in the study speculated that this behavior could have two explanations: the puppies are trying to assess if they are in danger of life or the puppies are testing the type of hierarchical relationship they have with these adults, as at their age they still don’t know it and they must experiment to learn it (Duchesneau et al. 2022). Pending further studies confirming this fact and further research debating the issue, we can ask ourselves whether the tear in little humans is also an instrument of defense against infanticide. It may be that sometimes in the history of humanity the too feeble cry of a child has led the parents to abandon the sickly child or to kill him; but that this may be a sign of systematic induction to the divestment of parental care appears implausible. As we will see in §2, some neurodevelopmental disorders, such as autism, seem to cause anomalies in the acoustic signals of crying, but no parent would kill the baby because he imagines from crying that he has little chance of survival or of enjoying the same state. Physical and mental health of the average of other children in the country. Very frequently, children with a somewhat compromised state of health show crying that deviate from the norm (Furlow, 1997; Soltis, 2004), but infanticide is rare. Furthermore, when a child has serious health problems, his/her poor chances of survival are unfortunately inferred from much more serious and evident signs that crying, if it plays a role in the choice of caregivers to commit infanticide or abandon it, is probably a secondary role. Even when infanticide is understood as a sort of euthanasia, such as in the case in which the puppy is so sick that it cannot survive except in atrocious suffering, in reality for those who materially commit the murder, the crying - that is vigorous or weak - will likely induce the negative feeling of doing something against their feeling. Finally, it should be noted that perhaps, if fetuses

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3 Emotional Tears: A Human Uniqueness

could cry and could do so in a visible and audible way, fewer countries would have institutionalized abortion. In 2020 the serial killer Donato Bilancia died in prison in Italy. He was sentenced to 13 life sentences for committing 17 murders; some committed in revenge, others because the victims by chance witnessed other crimes; still others to satisfy an impulse to kill suddenly flashed in his head. This is usually enough to let the public regard him as a monster with no mercy. Still, his murders would have been 18 if one of his potential victims, Luisa Cimminelli - a prostitute to whom he had already put a gun to her head - hadn’t burst into tears, begging him to spare her life so she wouldn’t abandon her two-years old baby. In the case of Luisa Cimminelli, a mother’s tears were metaphorically joined by those of her son, who would be left alone even breaking through a habitual killer. However, in the face of this episode, there are many others - unfortunately - that show the vulnerability of this peaceful weapon; or even how dangerous it can in some cases be for the mourner himself. The list of infants sadly killed by their parents or other caregivers because of their crying is horribly long. Just to give an example, we recall the case of the little Royality Kemp, killed when she was just 4 months old, in July 2021 by Ricardo Price, her mother’s partner. The man said he was seized by a fit of rage due to the annoyance he felt because the baby’s crying prevented him from concentrating on video games. The man had taken the child, threw her against the wall and then repeatedly hit her with the video game controller. He had finally put the baby in her crib, where the mother found her shortly after returning to home. Unfortunately, a huge part of the infanticides reported by the black chronicles are configured as a murderer’s desire to stop the baby from crying. Crying can trigger the murder of the mourner in many ways. The serial killer Michael Bruce Ross, in an interview with the journalist Christopher Barry-Dee, declared that he felt pain for the killing of one of his victims, Leslie Shelley, who died in 1984 at the age of fourteen. He admitted that he himself cried for her death after killing the adolescent. He said he talked to her for about an hour before killing her, despite having the opportunity to do it before; but he did it only after she began to cry. Describing what happened almost as a necessary flow of events: since it had to happen by force, it is better to hurry up and not continue beyond the suffering that acquired material reality through the victim’s tears (Barry-Dee, 2003). The tear is the unmistakable materialization of a feeling. Feelings manifest themselves in many ways in the body of human beings and the tear is one of these most visible manifestations. The tear can trigger different types of reactions in the recipient, but rarely those who witness someone else’s tears can ignore them. A witness to someone else’s tears can get excited or angry at them; he can turn them into future feelings of guilt or can choose to accept the request for help hidden in them; but ignoring them will by far be the most difficult behavior. Returning to the example proposed by Gračanin et al. (2018), it is true that sometimes a not vigorous crying is associated with low chances of survival and can become an unfavorable signal to those who emit it because it discourages the group to invest in them, this is not what is contested; what is contested is the idea,

3.6

The Weapon of Truth

31

implicit in the scheme of these authors, that universal reactions can be codified to the meaning of a signal. But how then does a signal be social, have an adaptive value by virtue of this signaling but not arouse the same reactions in all human beings and in all cultures? With the exception of this signal of babies crying, all other events reported in the study by Gračanin et al. (2018), orient the vision of tears as a tool for bonding and social cohesion. This scheme, however, overlooks the tears of joy and emotion that are also contemplated in the scheme of Vingerhoets (2013) when he considers for example the tears of an extraordinary performance or a victory. In general, the scheme of Vingerhoets (2013) has the advantage of also taking into account the tears of joy, while that of Gračanin et al. (2018) is clearer in highlighting the role of others’ reaction. It is no coincidence, however, that greater attention to the reaction of others leads to less attention for tears of joy. Let’s try to imagine an athlete shedding a tear for having had an extraordinary performance; not an extraordinary performance for the world, but an extraordinary performance for himself. The tear in this case has no real social value, but indicates to the subject himself, who makes himself public of himself, of the importance of what has just happened. If someone around him were to notice his tear of joy, they could intervene by complimenting him and making him even happier about the act he just performed or he could even decide to make fun of him even badly for his inappropriate joy and thus transform joy into shame; but this would not undermine its meaning as a guarantee of the authenticity and genuineness of the feeling just experienced. So when it is argued that the tear has a social value, it does not mean that it has the value of pushing people to prosocial behavior: this is the most common reaction and probably the one that has evolutionarily balanced the cost of crying. However, the only universal reaction to crying and which explains both the tears of pain and those of joy is the ascertainment of the genuineness and authenticity of the feeling experienced by those who cry and consequently the difficulty in completely ignoring the signal. Sometimes we only attest to this genuineness to us, as in the case in which we cry alone in front of an old blanket that our grandmother put on us to warm the bed when we fell asleep at her house, after having been to the amusement park with our other little cousins. But if someone saw us cry, we could expect different reactions from different people but all united by the perception that we are sincerely experiencing the feeling that our tears underline.

3.6

The Weapon of Truth

Let’s start from the beginning: crying is an expensive signal. A baby who cries profusely (1) consumes a lot of calories; (2) he becomes dehydrated (and therefore if he is still breastfed he forces the mother to breastfeed him more, with greater need to stay still and greater caloric expenditure for her); (3) if he vocalizes he runs the risk

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of attracting predators; (4) if he has already developed a tearful cry, the tears will cloud his vision. We are led to think that the positive side of this behavior will be that the mother or the social group to which he belongs will come to his rescue and will try to satisfy his needs; but this they would have done even if the child did not have wet eyes with tears, but would have done only the classic wailing for help of mammals and other animal species. Furthermore, as the child grows, the acoustic signal is increasingly replaced by the visual one, which progressively acquires greater significance. Why? The point is that tears are a visual signal that the feeling expressed is sincere and authentic. The advantage of the visual component is that it cannot be perceived by potential distant predators; on the other hand for those who are close and - as we have seen - ethologically led to pay attention to the eyes of others, so they will immediately receive a signal emitted by the eye and being this a tear, they will perceive it as a reliable signal on the emotional life of the subject who emits it. And who fakes tears to convince the audience? Tears have the power to make any signal clearer; a person who pretends an emotional state, with tears will only accentuate the pretense of him and will be treated as an impostor by the recipients of the signal. Therefore the universal psychological reaction to tears is to trust the signal associated with the feeling used; the behavioral reaction, on the other hand, changes according to the context: returning to the case of the child who emits a weak cry, it may be that in some parents it leads to abandonment and in others to a greater investment of care, but in both cases the crying will be considered a reliable signal in a more general context of signals emitted by the child. The reliability of the signal, the enhanced form that the signal assumes through the complement of a new material manifestation of it, that is the tear, also makes visible what would have been more easily ignored by a little receptive transmitter.

References Alexander, R. D. (1974). The evolution of social behavior. Annual Review of Ecology and Systematics, 5(1), 325–383. Balikci, A. (1967). Female infanticide on the Arctic coast. Man, 2(4), 615–625. Barry-Dee, C. (2003). Talking with serial killer. John Blake Publishing Ltd. Bodelier, V. M. W., Van Haeringen, N. J., & Klaver, P. S. Y. (1993). Species differences in tears; comparative investigation in the chimpanzee (pan troglodytes). Primates, 34(1), 77–84. Bylsma, L. M., Gračanin, A., & Vingerhoets, A. J. (2019). The neurobiology of human crying. Clinical Autonomic Research, 29(1), 63–73. Dartt, D. A. (2009). Neural regulation of lacrimal gland secretory processes: Relevance in dry eye diseases. Progress in Retinal and Eye Research, 28(3), 155–177. Darwin, C. (1870). The expression on the emotions in man and animals. Cambridge University Press. (digitally printed version 2009). Duchesneau, A., Edelberg, D. G., & Perry, S. E. (2022). Are demographic correlates of white-faced capuchin monkey (Cebus capucinus) “Gargle and Twargle” vocalization rates consistent with the infanticide risk assessment hypothesis?. American journal of primatology, 84(1), e23344.

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Fossey D. (1983). Gorillas in the mist. Houghton. Furlow, F. B. (1997). Human neonatal cry quality as an honest signal of fitness. Evolution and Human Behavior, 18(3), 175–193. Gelstein, S., Yeshurun, Y., Rozenkrantz, L., Shushan, S., Frumin, I., Roth, Y., & Sobel, N. (2011). Human tears contain a chemosignal. Science, 331(6014), 226–230. Gračanin, A., Bylsma, L. M., & Vingerhoets, A. J. (2014). Is crying a self-soothing behavior? Frontiers in Psychology, 5, 502. Gračanin, A., Bylsma, L. M., & Vingerhoets, A. J. (2018). Why only humans shed emotional tears: evolutionary and cultural perspectives. Human Nature, 29, 104–133. Gračanin, A., van Assen, M. A., Omrčen, V., Koraj, I., & Vingerhoets, A. J. (2017a). Chemosignalling effects of human tears revisited: Does exposure to female tears decrease males’ perception of female sexual attractiveness? Cognition and Emotion, 31(1), 139–150. Gračanin, A., Vingerhoets, A. J., & van Assen, M. A. (2017b). Response to comment on “Chemosignalling effects of human tears revisited: Does exposure to female tears decrease males’ perception of female sexual attractiveness?”. Cognition and Emotion, 31(1), 158–159. Guyenet, S. J. (2017). The hungry brain: Outsmarting the instincts that make us overeat. Macmillan. Hrdy, S. B. (1979). Infanticide among animals: a review, classification, and examination of the implications for the reproductive strategies of females. Ethology and Sociobiology, 1(1), 13–40. Kardon, R. (2005). Anatomy and physiology of the autonomic nervous system. Wash and Hoyt’s Clinical Neuro-Ophthalmology, 6th edn (pp. 649–714) . Philadelphia: Lippincott Williams & Wilkins. Liang, H., Wu, S., Yang, D., Huang, J., Yao, X., Gong, J., ... & Peng, Q. (2022). Non-targeted metabolomics analysis reveals distinct metabolic profiles between positive and negative emotional tears of humans. medRxiv. Lummaa, V., Vuorisalo, T., Barr, R. G., & Lehtonen, L. (1998). Why cry? Adaptive significance of intensive crying in human infants. Evolution and Human Behavior, 19(3), 193–202. Mhlahlo, A. P. (2009). What is manhood?: the significance of traditional circumcision in the Xhosa initiation ritual. Doctoral dissertation, Stellenbosch: University of Stellenbosch. Montagu, A. (1960). Natural selection and the origin and evolution of weeping in man. J Am Med Ass, 174, 392–397. Murube, J. (2009). Tear apparatus of animals: Do they weep? The Ocular Surface, 7(3), 121–127. Murube, J., Murube, L., & Murube, A. (1999). Origin and types of emotional tearing. European Journal of Ophthalmology, 9(2), 77–84. Newman, J. D. (2007). Neural circuits underlying crying and cry responding in mammals. Behavioural Brain Research, 182(2), 155–165. Nguyen, D. H., Beuerman, R. W., Thompson, H. W., & DiLoreto, D. A. (1997). Growth factor and neurotrophic factor mRNA in human lacrimal gland. Cornea, 16(2), 192–199. Park, K. S., Kim, S. S., Kim, J. C., Kim, H. C., Im, Y. S., Ahn, C. W., & Lee, H. K. (2008). Serum and tear levels of nerve growth factor in diabetic retinopathy patients. American Journal of Ophthalmology, 145(3), 432–437. Picó, A., Gračanin, A., Gadea, M., Boeren, A., Aliño, M., & Vingerhoets, A. (2020). How visible tears affect observers’ judgements and behavioral intentions: Sincerity, remorse, and punishment. Journal of Nonverbal Behavior, 44(2), 215–232. Provine, R. R. (2011). Emotional tears and NGF: A biographical appreciation and research beginning. Archives Italiennes de Biologie, 149(2), 269–274. Roes, F. L. (1989). On the origin of crying and tears. Human Ethology Newsletter, 5, 5–6. Sneed, D. (2021). Disability and infanticide in ancient Greece. Hesperia: The Journal of the American School of Classical Studies at Athens, 90(4), 747–772. Sobel, N. (2017). Revisiting the revisit: Added evidence for a social chemosignal in human emotional tears. Cognition and Emotion, 31(1), 151–157. Soltis, J. (2004). The signal functions of early infant crying. Behavioral and Brain Sciences, 27, 443–490.

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Tennent, J. E. (1859). Ceylon, en Account of the Island, Historical and Topographical (Vol. 1). Longmann Green. Trimble, M. (2012). Why humans like to cry: Tragedy, evolution, and the brain. Oxford University Press. Vingerhoets, A. (2013). Why only humans weep: Unravelling the mysteries of tears. OUP Oxford. Walter, C. (2006). Why do we cry? Scientific American Mind, 17(6), 44–51. Woo, H. M., Bentley, E., Campbell, S. F., Marfurt, C. F., & Murphy, C. J. (2005). Nerve growth factor and corneal wound healing in dogs. Experimental Eye Research, 80(5), 633–642. Zahavi, A., & Zahavi, A. (1999). The handicap principle: A missing piece of Darwin’s puzzle. Oxford University Press. Zhang, B., Noble, P. L., Winslow, J. T., Pine, D. S., & Nelson, E. E. (2012). Amygdala volume predicts patterns of eye fixation in rhesus monkeys. Behavioural Brain Research, 229(2), 433–437.

Chapter 4

Eyes, Gazes and Language

“in truth the eyes are nothing more than lenses, it is the brain that actually does the seeing” Blindness Saramago

4.1

Face to Face with Mummy

What has been said so far clearly shows that the eyes, in addition to taking on the function of allowing us to see, play a very important role in intraspecific communication. Some characteristics of the human eye, such as the anatomy and the emotional tears, are unique to the human species. As we saw in the first chapter, the anatomy of the human eye in fact always allows conspecifics to know where we are looking; furthermore, as we saw in the second chapter, the tear makes the eye the most reliable tool for verifying the truth of certain emotionally salient signals. It is therefore no coincidence that the eye has been at the center of various theories on the origin of language. The purpose of this chapter is to analyze some of these. This paragraph will present the thesis proposed by the psychiatrist Herbert S. Terrace of Columbia University (NY) in an essay published in 2011 entitled Missing Links in the Evolution of Language. In this work, the psychiatrist criticizes the Chomskyian view that language suddenly emerged about six million years ago; language would instead develop, in his opinion, slowly starting from pre-linguistic conversations and evolving only later in articulated language. Let’s see how. Terrace starts from the observation that when hominids switched to bipedalism, their structure underwent a reduction of the pelvis which in turn led to a reduction of the birth canal. The latter in turn led to a reduction in the maximum possible brain volume in the newborn: the result was that hominids now, just born, have brains that are about 20% of the total volume of what they will have as adults; on the contrary, a newborn chimpanzee’s brain (our closest cousin among the living) is about the 40–50% of the brain volume that it will have when adult. In the transition from Homo erectus to us, there were then two other physical changes of interest to © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Pennisi, Gazes, Words, and Silences in Pragmatics, Perspectives in Pragmatics, Philosophy & Psychology 36, https://doi.org/10.1007/978-3-031-42571-4_4

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illuminate the debate on language acquisition: the loss of body hair and the development of a white sclera (which was previously dark) in chromatic contrast with the iris. The lack of hair in the mother’s body makes it impossible for the baby to hang on to her body as non-human primates still do today. Compared to the puppies of non-human primates and probably also compared to the children of hominids that come up to Homo erectus, the puppies of humans are much more unprepared from the motor point of view due to the still small size of the brain and also to the impossibility of hanging to the mother’s body. These two characteristics mean that the mother has to spend a lot of time with her baby in her arms, holding him in the classic face-to-face position. This is where the central role of the eye according to Terrace would come into play: the most salient stimulus in the visual landscape of the child is now the gaze of the mother. The eyes in primates are already a salient stimulus before Homo erectus, but the whitening of the cornea and therefore the contrast with the iris would make them much more expressive. At this point, the human structural peculiarity is transformed, in Terrace’s theory, into a relational peculiarity: the mother and the child continually exchange one another glances thanks to which the child learns and acquires a sense of self, without which it is impossible to speak of language. Most important is the time the infant and the mother gaze at each other. The outcome of those interactions can produce different emotional reactions in the infant and the mother. Those reactions are essential for the regulation of an infant’s emotional state. For example, an infant’s expression of fear can be quickly replaced by the mother’s smile and her expression of contentment can be quickly replaced by the mother’s frown or by non-engagement. It is through these hour-by-hour interactions with her mother that the infant is said to develop a sense of other. She cannot always predict when her mother will smile or frown but she can recognize when her mother’s emotional state differs from hers. As far as I am aware, such interactions have not been observed in other primates. To be sure, there are examples of mutual eye gaze, laughter, etc., but there is no evidence that they can be sustained with anything that approaches the intensity of the mother - infant relationship in humans (Terrace, 2011, p. 20)

Herbert Terrace then concludes his reasoning with the incipit “joint attention requires eye gaze” (ibid., P. 12) arguing that, thanks to this exchange of glances, the child slowly begins to share attention with the mother by opening up so to the triadic adult-child-object of attention relations; the latter are the prerequisite for the ontogenetic and phylogenetic acquisition of language.

4.2

Cooperative Gazes

Before explaining what exactly the cooperative eye theory consists of, it is useful to contextualize it in Michael Tomasello’s more general theory of language development. Tomasello considers human language a derivative of the development of human capacity to cooperate. Although all gregarious species always have some form of cooperation, the human one - according to Tomasello - is unique because it

4.2

Cooperative Gazes

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assumes both an understanding of individual intentionality and the use of shared intentionality. This last notion is a central element of Tomasello’s theory; this in turn, is deeply rooted in Wittgensteinian philosophy. It is not possible to fully understand Tomasello’s perspective if it is not first of all brought back to Wittgenstein’s notion of language as praxis. Tomasello mentions Philosophical Investigations very often, openly declaring his debts to Wittgenstein especially in relation to two themes: the notion of form of life and the peculiarity of demonstratives. However, I think that is the praxiologic view of language (to which obviously both of these theme are linked) which in a broader way it defines Tomasello’s entire approach. In his Philosophical Investigations, Wittgenstein emphasizes the analogy that exists between the specific characteristics of different instruments which share the characteristic of being able to be used with the hands and words. All tools that are used with the hands, for example, will have some similar characteristics related to the fact that we use them with the same part of the body; likewise they will have very different characteristics due to their different use. In the same way words have something in common (for example the fact that they are said) and at the same time that diversifies their meaning. What makes meanings different is not only and essentially their signifier, but often precisely the use we make of them, exactly as with instruments. And so I use the same word “mom” in a different way if I call my mother by saying “mom”; or if I say “Samuel’s mom is blonde” or if I say “Oh my goodness, mom! What a fright!”. What determines the meaning of the word “mom” in these cases is the context of use. The analogy between words and tools continues even when Wittgenstein talks about classifications: how we classify tools depends on the purposes of our classification. We can imagine a language that is homogeneous in its categories of uses: for example a language that consists only of information or one that consists only of orders given in combat: “And to imagine a language is to imagine a form of life” (Wittgenstein §19). Language is not an abstract and disembodied entity, but it is used by a community of speakers in specific dynamics of interaction which fully enter into the meaning of the speech act (on the praxiological character of language games see also Voltolini, 2006). This approach to the philosophical study of language problems is an indispensable theoretical presupposition for the development of Tomasello’s theory which we will deepen in the next paragraphs.

4.2.1

Individual Intentionality and Shared Intentionality

If, in non-human primates, vocalizations appear innate inflexible, in those phylogenetically closest to humans (especially bonobos and chimpanzees) visual communication is very flexible as there are communicative gestures that are learned during ontogenetic development and that are then used intentionally throughout life. For Tomasello in general, gestural communication in non-human primates is special

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because, among the gestures learned, there are also intentional acts that operate with a meta-intentionality: that is, making the other see and act by virtue of what he has seen. This type of communication assumes the understanding and voluntary use of the intentionality of others (individual intentionality). That is, whoever emits the signal must have some knowledge of how the receiver receives the signal and must act according to that. To explain this concept, we will report some examples cited by Tomasello himself. The first example concerns the fact that chimpanzees respond differently to similar human actions in terms of physical appearance, but different in intentionality: specifically Call et al. (2004) showed that chimpanzees get angry if a human stops giving them food for no apparent reason; but they wait patiently if the human does not offer them food because it is impossible or hindered by other physical agents. This behavior is similar to that of infants from 9 to 18 months of age, but absent in infants of 6 months, who do not seem to distinguish between these two types of behavior at all (Behne et al., 2005). Another example of individual intentionality concerns helping behaviors: both human infants (18–24 months) and chimpanzees help, if they are physically able to do it, a conspecific to reach an object beyond its reach (Warneken et al., 2006; Warneken & Tomasello, 2006). This behavior, as rightly argues Tomasello, requires an understanding of someone else’s goal. Just to give a final example, if you train chimpanzees to imitate humans by performing actions on some objects; chimpanzees are able to distinguish between actions performed accidentally and voluntary actions (and therefore only perform those performed voluntarily by humans, ignoring the accidental ones; see Tomasello & Carpenter, 2007). This behavior is similar to that of 18-month-old human infants (Carpenter et al., 1998). But in addition to individual intentionality, human beings have another faculty: shared intentionality. Tomasello calls in support of the idea that the foundation of human cooperative communication derives from shared intentionality the philosophies of Wittgenstein, Grice, Lewis, Sperber, Wilson, Clark, Levinson and Searle. He argues that communication conventions arose out of conjoined ends and that special human speech skills likely evolved to facilitate conventional communication and to distinguish group members from strangers to the group. In these terms he defines language: “Language, or better linguistic communication, is thus not any kind of object, formal or otherwise; rather it is a form of social action constituted by social conventions for achieving social ends, premised on at least some shared understandings and shared purposes among users” (Tomasello, 2008:343). So what is the human peculiarity compared to other primates? “human beings are the only animal species that conceptualizes the world in terms of different potential perspectives on one and the same entity, thus creating so-called perspectival cognitive representations [. . .]. The key point here is that these unique forms of human conceptualization depend crucially on shared intentionality—in the sense that the whole notion of perspective presupposes some jointly focused entity that we know we share but are viewing from different angles” (ivi). Tomasello and Carpenter (2007) tried to clarify this difference between individual intentionality and shared intentionality. Shared intentionality would be a sharing of

4.2

Cooperative Gazes

39

psychological states, in order to create a common interpretative background, but in which each participant in the conversation knows that his point of view is different from that of others. Authors give an example of how children and chimpanzees interpret the indicative gesture during play sessions. If an adult indicates a child a bucket with a stain, the child has no way of knowing whether the object of reference is the bucket or the stain. But if an adult and a child are playing looking for toys, the child will interpret the gesture as a potential suggestion of finding the toy “ah let’s see if the toy is inside the bucket”. The chimpanzee, on the other hand, will not take the hint. The authors paraphrase this behavior by metaphorically attributing to the chimpanzee a thought like “a bucket? So? Where is the food I’m looking for? “. So let’s go back to the example of chimpanzees who help conspecifics to get out of the cage. The chimpanzee that comes out of the cage is not asking the other chimpanzee explicitly for help and cooperation, it is just trying to get out of the cage. The assistant sees the scene, understands that the other is trying to get out and helps him. Let us now consider the different case of a human being inside a cell and asking another human being outside the cell to let him out. In this case, the attention is shared since the person locked up, through his words (or any other gestures with which he is asking to go out), captures the attention of the other on his situation, asking him to share the state with him. Psychological of him. Not the action he is trying to do (for example, opening the cage); not the perception of him; but his psychological state, that is, his desire to get out of the cage. Both are sharing the intention of carrying out a communication. The information relating to this desire is not transmitted through an interpretation of a goal directed motor act, that is, the receiver is not seeing the broadcaster trying to perform the action of getting out of the cage. The information relating to this desire is voluntarily transmitted from one to the other through a gesture, a sentence, a tool with which the psychological state of the emitter is communicated. Therefore, for Tomasello and Carpenter (2007), understanding the intentional perception of a conspecific or understanding its action is possible for chimpanzees; sharing the psychological state of the other, however, does not. But what is that ability that the chimpanzee doesn’t have? What does “reading the psychological state” means in practice? Faced with an ostensive act, the chimpanzee reacts (and not always) by turning towards the reference object; a human being, on the other hand, wonders what the sender’s intention is in directing his attention to that reference object. But Tomasello (2008) underlines that, in order for the answer to this question to be reliable, it is necessary that the sender and receiver share what Wittgenstein called a ‘form of life’ (Wittgenstein, 1953), that is the peculiar situations of interaction: command and act according to the command; describe an object based on its appearance and size; constructing an object based on a description or drawing; report an event. A life form is a setting in which speakers explicitly or implicitly agree on what is being done. The fundamental cognitive ability of joint intentionality is recursion: not only I know that you know, but I also know that you know that I know, or I know that you know that I know that you know and so on potentially up endlessly. When the recursive reading of the mind is applied to common motivations, cooperation and

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communicative intention in the Griceian sense are born. Linguistic signs originate from a drift towards the arbitrary of the more “natural” deictic and iconic gestures. In this conceptual framework, ontogenesis would provide, according to Tomasello, various proofs of the importance of shared intentionality for the development of language. They are as follows: the deissi emerges simultaneously with the emergence of shared intentionality in the cooperative action; iconic gestures are born drawn from deictic ones but unlike the latter they are quickly replaced by verbal language. Therefore, according to Tomasello, human cooperative communication emerged as an adaptation to the general aptitude to collaborate of the species: as in ontogenesis, so also in phylogeny the shared intentionality led first to the use of deictic gestures, then of the iconic ones and then the drift towards the arbitrary of the latter, it allowed communication even to individuals who progressively shared less and less common ground. Vocal language has therefore developed only thanks to the previous possibility of using communicative gestures based on contingent action.

4.2.2

Cooperative Gaze, Lying Gaze

Within this theoretical background, let’s now look at how Tomasello et al. (2007) have articulated the theory of the cooperative eye. The scholars started from the observations on the peculiar morphology of the human eye that we have seen in § 1.1: from a phylogenetic point of view, the human eye is the one with a greater chromatic contrast between sclera and iris and with greater possibility of movement on the horizontal axis; these two characteristics make it the most informative of all primate eyes about the object of the viewer’s visual attention. According to Tomasello et al. (2007), since individuals competing with the beholder could benefit from this information to seize the resources he is aiming for, the fact that the eye in humans has developed with this particular conformation presupposes particularly cooperative conspecifics, towards which sharing of information does not entail major disadvantages (as would be the case with non-human primates). In support of this idea, the scholars bring the empirical data they themselves produced according to which, while, to identify the object of a subject’s visual attention, the great apes pay more attention to the direction of the head, children aged 12 and 18 months pay more attention to the direction of the eyes. Since with the sclera man can also lie (for example pretending to be attracted to something that is in the opposite direction to where his primary objective is) Segal et al. (2016) shifted the emphasis from the cooperative to the communicative role of the eye. Michael Tomasello’s perspective is interesting because it highlights the advantages of cooperative communication with the eyes and the possibility that the eyes of human beings, particularly flexible and expressive in communication, can enhance the communicative power in humans. However, as we will try to show in the next paragraphs, the role of ocular communication appears to us to be excessively valued

4.3

The Gaze Advantage: Empirical Studies

41

in this perspective. Tomasello (2008), citing Bloom (2002), argues that all those who do not believe that language acquisition is a social process, but simply a process of association between words and things, will never understand why learning (understanding) of speech begins at 12 months (the age at which, in Tomasello’s reconstruction, children begin to develop the cognitive infrastructure of shared intentionality) and not at 3 months or 3 years. In the next paragraphs, we will try to answer this statement by Tomasello by proposing an alternative answer to his to the question, “Why do babies start talking at about twelve months of age?”

4.3

The Gaze Advantage: Empirical Studies

This vision, which in recent years has received more and more successes from the close link between the emergence of language in phylogeny and the intraspecific ability to read the gaze, has its counterpart in a proliferation of theories that associate the development of language with the ability to read the gaze of others at the ontogenetic level. The basic idea of these studies is that it is easier for children to understand the referent of the words heard by adults if they are able to disambiguate, through the reading of the eyes of the latter, which is the object of attention of the adult (Baldwin, 1995; Bruner, 1983; Tomasello, 2003; Brook and Meltzoff 2005). The authors who perhaps most of all put the question in clear terms are Baldwin and Moses (2001), when they reflect on the fact that learning to ignore potential links between words and objects that are not relevant to them is at least as important as learning to connect words to the right objects: if the mother picks up an apple and says “apple” while looking at the fruit, the child is not only exercising his ability to understand the reference of the word “apple”, but at the same time also to exclude that the reference object is the bracelet worn by the mother. Eyes or not, it is clear that the connection between words and objects in developmental age is greatly helped by an underlying social understanding that precedes the use of language. So, studies in this direction are of two kinds: the first one is composed by reasonably moderate theories in which the socio-pragmatic component is considered one of the many factors contributing to the development of language; the second one is instead more oriented towards recognizing the social component as foundational and irreplaceable (Hollich et al., 2000; Baldwin & Moses, 2001). In 1993, Baldwin obtained an interesting data from an experiment conducted with 19–20 month old children: making an object salient with manipulation while naming it is not enough to induce children to associate the name of the object with the reference object; what is decisive for learning to be successful seems to be the adult’s gaze turned towards the object. Already in 1998, Morales and collaborators, encouraged by the first publications on the subject of Tomasello, began to test the link between the ability to align one’s visual attention with that of caregivers in newborns and future language development. In a controlled experiment of observation of mother-infant interactions at 6 months and a subsequent follow-up on language development, the researchers

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actually found that infants who at 6 months more frequently tend to align with the mother’s visual attention, will show greater receptive language skills at 12 months and productive at 18, 21 and 24 months. In 2000 the same research group replicates the data with an even larger sample of children (Morales et al., 2000b, 2000a); however, a further examination of the literature led them to wonder if the development of prelinguistic vocalizations was not a significant predictor of language development and they actually realized that the predictive value of the latter was at least equal to that of the development of shared attention (Morales et al., 2000a). On the same wavelength, a few years later, Brooks and Meltzoff (2005) found that if, on average, still at 9 months, newborns mostly follow the orientation of the head of their communicative partner, at 10 months they follow the eyes. This is a significant step forward in acquiring the ability to read the intentional states of others. They too, after having quantified the propensity of infants to follow the gaze of others, put it in relation to the language skills shown at 18 months: also in this case the children who were more attentive to the adult gaze had better linguistic comprehension skills at 18 months, but not a richer linguistic production. Specifically, if the children followed their gaze on a reference object while the adults named it, the word was more easily learned than with vocalization alone. This data, although according to the authors would support the idea that following the gaze of others plays a role in the acquisition of language, nevertheless sheds light on an important factor: on the admission of the authors themselves, the productive component of language, on the other hand, could be based on other factors. So, a few years later, the same authors verified with a longitudinal study the nature of the relationship between the ability to follow the gaze of others and the development of productive language in children from 10 to 24 months. Specifically, the ability of children to follow the gaze of adults at 10 and 11 months was evaluated and then this was related to the development of productive language between 10 and 24 months (statistically controlling the effect of the maternal education level). All children had a vocabulary explosion at 14 months, as was naturally expected, but children who at 10–11 months followed adult gaze longer and looked longer at objects than adults looked at, had a greater explosion of vocabulary during the follow-up. However, the researchers also found those children who were not particularly good at using the adult gaze for reference fixation, even though they developed a statistically less rich language than those who were better at gaze tracking, still developed an average language: for these reasons the authors conclude that the gaze gives children an advantage in the acquisition of words (Brooks & Meltzoff, 2008), but not that it is indispensable. A study conducted once again by the same researchers then clarified a non-negligible detail: that part of the semantic baggage that children who follow the gaze of adults more have compared to others is mostly composed of mentalistic terms (Brooks & Meltzoff, 2015). This of course, combined with the impossibility of correlational studies to clarify the causal link between the phenomena considered, leads us to ask whether the chicken or the egg was born first. In other words: children who follow the gaze more are simply more likely to learn the practices of the social and mental world (and therefore to acquire the vocabulary more quickly) or their attention to the gaze leads them to understand the others’ mind more?

4.3

The Gaze Advantage: Empirical Studies

43

Fig. 4.1 Two failed representations of the relationship between gazes, social cognition and language

In other words, a greater talent for eye following most likely leads to a better development in terms of quality and speed of language development and in general to a better development of social cognition. But in parallel it must be said that children with a more developed propensity for sociability will most likely tend to observe the gaze of others more. Obviously the two phenomena are not mutually exclusive: a child who has a particular talent for following the gaze of others will probably develop better social skills than others and simultaneously also become increasingly good at reading the gaze of others. Similarly, a child who is particularly good at orienting himself in the social world will probably cultivate more and more observation of the gaze of others over time. For these reasons, it makes no sense to ask whether the innate tendency to look more into the other’s eyes leads to a better development of social cognition (and consequently of linguistic and non-linguistic communication) or if the greater development of social cognition leads to a greater ability to read the gaze of others and consequently to a better development of language and a greater propensity to use the gaze for social orientation (Fig. 4.1). On the contrary, I would be inclined to represent the innate tendency to look more at the gaze of others, the development of social cognition and the development of language through the image of a cycle in which each element positively influences the others (Fig. 4.2). However, what happens first between these three phenomena when life begins we are not yet given to know and these experiments do not explain it to us. That is, we do not know which of these three phenomena occurs first and to what extent they influence each other. In other words, these experiments do not tell us if (and, if yes, which of) these skills develop before the others. These studies don’t even tell us how much these three variables influence each other even if they seem to indicate that gaze reading is not indispensable for the development of language. If I remove the tendency to look into the eyes of others and to use this cue to orient oneself socially, will social cognition and language still develop? In the next chapters, I will try to answer these questions. Specifically, I will try to show how in species phylogenetically distant from humans, the gaze is not at all necessary for the development of social cognition; but that it has only become more important as

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Fig. 4.2 Social cognition, language and tendency to look more into the others’ eyes influence each other

Fig. 4.3 The proposed relationship between language development and social cognition. This scheme does not invalidate the previous one because the reading of the gaze of others, when present, is inserted between the two variables as indicated in the previous figure; however, we will try to show in the following pages that it is not essential to the development of language and social cognition

one approaches the genus homo. I will also try to show how in humans the development of social cognition is fully possible even when the subject (for reasons we will see) does not develop the ability (or does not have the innate competence) to use the gaze to interact socially. In these latter cases, the cycle represented in Fig. 4.2 becomes a bipolar linear representation without hierarchy (Fig. 4.3). This way of seeing the relationship between gazes and language has obvious philosophical implications: language, while maintaining a certain ontological autonomy from social cognition, is strictly dependent on it and at the same time shapes it in its turn, but the observation of the others’ gaze is not necessary for the interaction between these two cognitive processes. These experiments, although they seem to demonstrate the role that the eyes play as facilitators of communication and above all of the connection between objects and words in the critical months of the development of the receptive vocabulary, also indicate the possibility of children to pursue alternative paths to the use of the index function that the eyes can take.

4.4

4.4

And So? What Happens to the Link Between Gazes and Language?

45

And So? What Happens to the Link Between Gazes and Language?

The two theories (Terrace’s and Tomasello’s) both have the merit of discussing some non-strictly linguistic aspects of human communication, which also make it unique, such as the need for an intensive presence of caregivers for a long time, facilitation empathic exchanges through the eyes, the role of the visual context for the disambiguation of dubious messages (such as the indication of a bucket with the stain). We can agree with the idea that social cognition is a phylogenetic and ontogenetic precursor of language. That is, language in man undoubtedly also has a communicative and therefore social function. Social cognition, however, certainly preceded it phylogenetically and precedes it ontologically: primates (and many other animals) have a highly developed social cognition and infants begin to develop their social cognition well before having acquired full linguistic mastery. As we saw in Chap. 2, however, it is not only the conformation of the human eye that makes this organ unique in the animal landscape, but also its close association with the truth value of the information transmitted, that is its capacity - through the emotional tears - to certify the reliability of an emitted signal. This aspect is rarely the subject of discussion in theories on the origin of language. A first criticism that could be made to both theories is the following: the attention that the authors pay to the anatomy of the eye does not take into account the phylogenetic dynamics. That is, there are more important body characteristics that must be evaluated in humans before reaching the color of the sclera because they involve greater risks for the fitness of the species. Both authors overlook the different conformation of the supralaryngeal vocal tract of humans and great apes. Why consider the difference in the color of the sclera more important and instead neglect the presence of a laryngeal configuration responsible for the constant risk of suffocation in humans? Another example of this methodological bias is the absence of a discourse on the tear. As we saw in Chap. 2, the emotional tear is energy-consuming and leads to dehydration. The white sclera, on the other hand, is less expensive than the dark one. Why pay attention to a phenomenon such as the change in the color of the sclera (which could also be explained only by considering the energy savings associated with it) but neglect the resources invested in demonstrating the reliability of the signal? Another objection that could be raised to both theories is that - although it is indubitable that the setting of shared attention by means of gazes favors the acquisition of language - the gaze is not the only tool through which one can induce a child to sharing attention. Moreover, if this were the case, children with congenital blindness and children with autism could never develop language. Other considerations then should also be made individually on the two theories. We can also agree with Terrace’s idea that the face-to-face interaction that is forcibly frequent between mother and child due to the child’s motor deficiencies and the impossibility of clinging to the hair can help to intensify the communicative use

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of mutual gazes. It is equally true that between a human mother and child there is a very dense emotional exchange in the first months of life; but this is not only not exclusive to visual communication, but it does not even begin through sight, but through hearing: the baby hears and recognizes the mother’s voice even before being given birth. Furthermore, it must be said that also in other animal species there is a very intense emotionally mother / child relationship. It is also worth spending a few words to question some points of Tomasello’s theory. This emphasis that he places on the extreme intraspecific vocation to cooperate is actually the result of an excessive coloring of some aspects of our species, and of a simultaneous obscuring of other more disturbing aspects, such as the fact that we are the only animals in the world to invest enormous resources to hit our conspecifics even mortally. Finally, the notion of language with which Tomasello works is more oriented on the communicative function rather than on the cognitive one of language. As we will try to show in the following pages, it is not possible to reconstruct the origin of language by neglecting its cognitive role. Language is not only a form of intraspecific communication, but also - and perhaps above all - a specific form of thought. The man, in addition to talking to the rest of the group, talks to himself when he thinks and elaborates his thoughts by words. The reduced consideration of the cognitive role of language emerges in many examples of referential communication brought by Tomasello in support of his thesis.

References Baldwin, D. A. (1995). Understanding the link between joint attention and language. Joint Attention: Its Origins and Role in Development, 131, 158. Baldwin, D. A., & Moses, L. J. (2001). Links between social understanding and early word learning: Challenges to current accounts. Social Development, 10(3), 309–329. Behne, T., Carpenter, M., Call, J., & Tomasello, M. (2005). Unwilling versus unable: Infants’ understanding of intentional action. Developmental Psychology, 41(2), 328. Bloom, P. (2002). How children learn the meanings of words. MIT press. Brooks, R., & Meltzoff, A. N. (2008). Infant gaze following and pointing predict accelerated vocabulary growth through two years of age: A longitudinal, growth curve modeling study. Journal of Child Language, 35(1), 207–220. Brooks, R., & Meltzoff, A. N. (2005). The development of gaze following and its relation to language. Developmental Science, 8(6), 535–543. Brooks, R., & Meltzoff, A. N. (2015). Connecting the dots from infancy to childhood: A longitudinal study connecting gaze following, language, and explicit theory of mind. Journal of Experimental Child Psychology, 130, 67–78. Bruner, J. S. (1983). Child’s talk: Learning to use language. W.W. Norton. Call, J., Hare, B., Carpenter, M., & Tomasello, M. (2004). ‘Unwilling’versus ‘unable’: Chimpanzees’ understanding of human intentional action. Developmental Science, 7(4), 488–498.

References

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Carpenter, M., Akhtar, N., & Tomasello, M. (1998). Fourteen-through 18-month-old infants differentially imitate intentional and accidental actions. Infant Behavior and Development, 21(2), 315–330. Hollich, G. J., Hirsh-Pasek, K., Golinkoff, R. M., Brand, R. J., Brown, E., Chung, H. L., et al. (2000). Breaking the language barrier: An emergentist coalition model for the origins of word learning. In Monographs of the society for research in child development (pp. i–135). Morales, M., Mundy, P., Delgado, C. E., Yale, M., Messinger, D., Neal, R., & Schwartz, H. K. (2000a). Responding to joint attention across the 6-through 24-month age period and early language acquisition. Journal of Applied Developmental Psychology, 21(3), 283–298. Morales, M., Mundy, P., Delgado, C. E., Yale, M., Neal, R., & Schwartz, H. K. (2000b). Gaze following, temperament, and language development in 6-month-olds: A replication and extension. Infant Behavior and Development, 23(2), 231–236. Segal, N. L., Goetz, A. T., & Maldonado, A. C. (2016). Preferences for visible white sclera in adults, children and autism spectrum disorder children: Implications of the cooperative eye hypothesis. Evolution and Human Behavior, 37(1), 35–39. Terrace, H. S., (2011). Missing links in the evolution of language. In S. Dehaene & Y. Christen (Eds.) Characterizing consciusness: from cognition to the clinic? Verlag Berlin Heidelberg: Springer. Tomasello, M. (2003). Constructing a language: A usage-based theory of language acquisition. Harvard University Press. Tomasello, M. (2008). Origins of human communication. Massachusetts Institute of Technology. Tomasello, M., & Carpenter, M. (2007). Shared intentionality. Developmental Science, 10(1), 121–125. Tomasello, M., Hare, B., Lehmann, H., & Call, J. (2007). Reliance on head versus eyes in the gaze following of great apes and human infants: The cooperative eye hypothesis. Journal of Human Evolution, 52(3), 314–320. Voltolini, A. (2006). Guida alla lettura delle “ricerche filosofiche” di Wittgenstein. Laterza. Warneken, F., & Tomasello, M. (2006). Altruistic helping in human infants and young chimpanzees. Science, 311(5765), 1301–1303. Warneken, F., Chen, F., & Tomasello, M. (2006). Cooperative activities in young children and chimpanzees. Child Development, 77(3), 640–663. Wittgenstein, L. (1953). Philosophical investigations. Basil Blackwell.

Chapter 5

What Does We Share with Other Animals?

“No, it’s finished, replied the old woman with a sudden expression of mistrust in her sightless eyes, a way of speaking that is always used in similar situations, but it has no basis in fact, because the eyes, the eyes strictly speaking, have no expression, not even when they have been plucked out, they are two round objects that remain inert, it is the eyelids, the eyelashes and the eyebrows, that have to take on board the different visual eloquences and rhetorics, notwithstanding that this is normally attributed to the eyes” Blindness Saramago

5.1

Phylogenetic Development of Eyes’ Meaning

From a phylogenetic point of view, vision has not always been what it is in man. Let’s take two simple examples. The aquatic beetle larva orientates itself with the light to identify the air, moving towards the latter. It is a behavior strictly encoded in the genes, so much so that if it is placed in an aquarium that is illuminated from below, the animal will follow the light and, finding no air, it will suffocate (Schöne, 1962). Proceeding one small step along the phylogenetic ladder towards the homo genus, we encounter the numerous frog vision neurophysiology experiments conducted in the 1970s and 1980s (Ingle, 1973, 1975, 1980, 1982). These showed that independent and parallel visual neural pathways are present in the frog. Specifically, we can distinguish a neural path (called tectal) for the identification of prey and predators (which actually seems to be further subdivided, but for simplicity we will stop here) and another neural path (called pretectal) that the animal instead uses it to control locomotion through the physical barriers of the environment. With an injury to the tectal path in a visual hemifield, the animal stops generating predation or flight-away behaviors if the inputs occur in the hemifield contralateral to the lesion, but maintains the ability to move correctly through the environmental barriers in that same visual hemifield.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Pennisi, Gazes, Words, and Silences in Pragmatics, Perspectives in Pragmatics, Philosophy & Psychology 36, https://doi.org/10.1007/978-3-031-42571-4_5

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It is plausible to hypothesize that vision, as one proceeds along the phylogenetic scale towards homo, has gradually become more and more complex and, as we will try to show, in this complexification the vision of the eyes of other individuals has found a special cognitive location. The eyes are often a salient stimulus for many animals. Eye detection is primary because being stared at by another individual is often considered, in the animal world, a threat signal as a predator that is about to attack prey must first look at it to identify its exact position. Eyes are often a warning sign for reptiles. Black iguanas (Ctenosaura similis) for example are able to interpret the direction of the gaze of a human being and to understand, based on it, if they are in danger or not (Burger et al., 1992); they escape faster if they see a man with a mask simulating huge eyes approaching them rather than a man with a mask simulating smaller eyes (Burger et al., 1991). Similarly, they run away more quickly if a person with an uncovered face runs towards them than if a person with a concealed face does (Burger & Gochfeld, 1993). Newborn pig-faced snakes (Heterodon platirhinos) activate their defensive strategy of pretending to be dead when confronted with an eye-like stimulus (Burghardt & Greene, 1988). Recently it has been shown that the red-legged tortoise (Geochelone carbonaria) is even able to follow the gaze of its conspecifics (Wilkinson et al., 2010). The eyes are a salient stimulus even if not necessarily perceived as an index of a potential threat, for example in fish they can modulate aggressive behavior but are often also the main clue for the recognition of conspecifics: Karenina et al. (2013), for example, showed how in the Amur sleeper fish (Percottus genii) the eye is the trigger for the social response; or again, Volpato et al. (2003) showed that in the Nile tilapia (Oreochromis niloticus) the color of the eyes of the fish is an index of social rank and at the same time modulates some intraspecific aggressive behaviors. In some species, such as the jewel fish (Hemichromis bimaculatus) (Coss, 1978) or the narcissus cichlid (Neolamprologus pulcher) (Kawasaka, 2021), it has also been shown that the gaze detection has a social significance and that it significantly modifies the behavior of the fish. Fish, like human infants, are also likely to have a holistic perception of faces, at least it has been experimentally observed in medaka fish (Oryzias latipes) (Wang & Takeuchi, 2017) and narcissus cichlid (Kawasaka, 2021). In birds there are social behaviors linked to the recognition of the co-specific; for example, roosters (Gallus gallus) tend to avoid having to exchange direct glances with other individuals and usually close their eyes if they meet the gaze of a co-specific (Jones, 1980). And, just like human infants, newborns show an innate preference for those visual stimuli that have the semblance of a face (Salva et al., 2011; Johnson & Horn, 1988); in this preference, the eye region plays a role of primary importance (Salva et al., 2011). In 1991 Morton and Johnson hypothesized that rooster behavior could be explained with the CONSPEC and CONLERN two-process model they had developed for human infants. But it is also very interesting to note that even more complex abilities related to gaze recognition seem to emerge in birds, that is the ability to identify the object of attention of a gaze. Wild geese (Anser anser), which are highly social birds and vulnerable to

5.1

Phylogenetic Development of Eyes’ Meaning

51

attacks by aerial predators, are able to follow the gaze of co-specifiers within the first six weeks of birth (Kehmeier et al., 2011). It is thought that the emergence of this ability is a factor of protection from predation: identifying the object of attention of conspecifics helps to identify potential incoming dangers. Tit (Poecile carolinensis) and great tit (Barolophus bicolor), in addition to considering the gazes of individuals of other species as a signal of risk of predation, seem to use the orientation of the gaze of the potential predator to infer where he is looking (Kyle, 2021). The hermit ibis is able to follow the gaze of its conspecifics (Loretto et al., 2010). Crows are also able to follow the gaze of other individuals, even at great distances and through physical barriers that blunt the visibility of the object of attention (Bugnyar et al., 2004; Schloegl et al., 2007). For many non-primate mammals, eyes also have a special communicative status. Although in dogs the olfactory perception is more important and acute than the visual one, the visual exploration of the face of others allows the recognition of familiar individuals even without the support of olfactory stimuli. In this visual exploration, the eyes of the observed subject play a role of primary importance, as we have seen in fish (Somppi et al., 2014). Dogs are able to maintain eye contact with humans for a long time (Johnston et al., 2017), in general domestic dogs increase their communicative behaviors when they are looked into the eyes by their owners (Savalli et al., 2016). In some cases they seem to have the ability to follow the gaze of man, even when this is not their owner, this is at least what Hare and Tomasello observed experimentally in 1999 in 5 of the 10 domestic dogs (Canis familiaris) they tested. Téglás et al. (2012) found that the condition for a dog to be able to follow the gaze of a human is that the ostensive act is preceded by an expression of the intent to communicate, such as a direct look at the dog or a voice call. As the experiment conducted by Hernádi and collaborators in 2012 shows, it seems in general that it is the effect of domestication that makes dogs able to sustain prolonged gazes with humans. In fact, these researchers compared the performance of two species of phylogenetically related but living ferrets, one in the wild (Mustela hybrids) and one domesticated (Mustela furo) and those of domestic dogs in tasks that required the animal to use the eyes of a human experimenter as an indexal: the two domestic species, which had similar performances, performed better. The importance of the role of domestication was also confirmed in a comparison study with chimpanzees in which it was shown that long contact with humans trains dogs (and children) to expect an ostensive signal (such as being watched in the eyes or being called by name), before a referential signal (such as looking at a potential object of attention) (Kano et al., 2018). Despite this, undoubtedly a genetic component must allow the animal to develop this type of communication, in fact, other animal species, even if long domesticated, such as horses, do not seem to be influenced by eye contact with humans (Verrill & McDonnell, 2008). Not surprisingly, usually the animal species able to follow or respond in some way to the gaze of humans, also make use of information from the eyes of other conspecifics, for example, domestic sheep are influenced by the gaze of humans, they don’t consider it a danger signal (Beausoleil et al., 2006); at the same time, they are able

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to co-orient their visual attention with that of the conspecifics and to consider the gaze of the conspecifics as a possible clue to find food (Kaminski et al., 2005). For ungulates, another individual’s gaze directed at them is a danger signal (Van Lawick-Goodall & Van Lawick, 1971). Even common mice (Mus musculus domesticus) do not seem indifferent to eye patterns (Topál & Csányi, 1994). That the detection of the gaze of other individuals is a very important phenomenon in the animal world is also revealed by the existence of the so-called ocelli. An ocello is a circular spot on the body of an animal made up of colors that contrast strongly with the surrounding parts. Ocelli often include several concentric rings and normally occur in symmetrical bilateral pairs in the animal’s body. In short, ocelli are spots that greatly resemble a pair of eyes. They are very frequent in Lepidoptera and are also widespread among Coleoptera, Fulgoridae, Orthoptera and in some tropical fish. The dik dik, small African antelope, have small black eye-like spots near the real eyes that probably help confuse any predators (Murube, 2009). There are many researchers who claim that ocelli have a protective function for the individual who exhibits them, as predators could be inhibited from attacking prey due to this perception of a glance. Numerous studies have in fact demonstrated the inhibitory effect of these spots and the most common interpretation is that the predators of those who exhibit them are in turn afraid that the ocelli are actually the eyes of predators (Stevens, 2005). In other cases, ocelli seem to be directly associated with reproductive success. The male peacocks, once the tail is opened, flaunt a very high number of ocelli with iridescent colors; as is known, the peacock’s tail is very important during courtship, when the males must be noticed by the females. Well, two researchers have recently shown that by altering the color range of these ocelli and making them white, previously successful males are then completely ignored by females (Dakin & Montgomerie, 2013). Although the number of ocelli present is not the only parameter on the basis of which peacocks choose their partner, peacocks with few ocelli are excluded a priori (Dakin & Montgomerie, 2011). The perceptual salience of the other’s gaze has manifested itself in different phylogenetic lines, therefore this ability has evolved several times in the biological history of the Earth.

5.2

Three Ways of Looking at Looks

As we have seen, the eyes are a communication tool in a large part of the animal world and this communication tool is spread patchily, that is, it has been positively selected by nature numerous times even without direct phylogenetic links. But when eye contact occurred in primates, the situation became more complex. According to Emery (2000) the communicative function of the eyes changed once it reached the primate branch. As we will see, in fact, on average, many primate species, in addition to being able to detect the gaze of other individuals, are able to follow it and in some cases to use it as an index to infer on which object to share

5.2

Three Ways of Looking at Looks

53

a object of Y's attention

observer X

observed Y

b In order to be able to see what is the object of Y's attention, X moves to a position which allows him to do so

observer X

object of Y's attention

observed Y

Fig. 5.1 Geometrical gaze following

attention with the other individual. Recently, the scientific literature has begun to distinguish three different types of gaze following: an automatic and reflected response to the gaze of the other that pushes the individual to co-orient his attention with the other; the main function of this behavior is probably to be able to identify the presence of any predators. We will refer to this kind of gaze with the expression “reflex gaze”. The second type of gaze following is instead a sort of “intelligent” gaze; in this case the subject physically moves in space to be able to observe the object of attention of the other’s gaze, even in spite of the presence of physical barriers which would require the observer to resort to geometric reasoning (cf. Figure 5.1) (Gómez, 2005). Animals capable of performing this type of visual pursuit are also able to understand the other animal’s visual perspective, and therefore to know what the other animal can and cannot look at from the position in which it is located. This ability is more common in animals that live in large groups with complex social rules, such as many primates (Hare et al., 2001). We will refer to this kind of gaze with the expression “geometrical gaze following”.

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Finally, a last type of gaze frequently evaluated in studies on communication is the so-called “double gaze”: in these cases the animal, after having followed the gaze of another individual (conspecific or not) and having identified its object of attention, once again he look at the other individual’s eyes to understand if other salient information on the target object can be drawn from it. According to many scholars this double check would certify that whoever follows the gaze has expectations of meaning related to the gaze (Butterworth & Cochran, 1980), simplifying a bit and anthropomorphizing as one should never do, we could imagine that the observer said to the individual observed “ok, that’s the object, what is the message you want to associate with the view of this object? That is, why did you point it out to me?” or “why are you looking at this?”. We will refer to this kind of gaze with the expression “double gaze”.

5.3

Social Structure and Body Structure Influence the Use of Indexical Cues

The elements that influence the way in which the eyes are used for communicative purposes in primates are essentially of two types: the first is the social structure of the species; the other its body conformation. To demonstrate that the social structure of the species influences the aptitude for the social use of the gaze is the fact that some primates that in the wild state may not use this form of communication much, nevertheless prove to be capable of it if these skills are elicited by human experimenters. We will devote several observations to the relationship between social structure and the use of gazes for communicative purposes in the following pages, when we will describe in more detail the social behavior of some primate species and the way in which they use and interpret gazes. On the other hand, as regards the relationship between body conformation and use of the eyes for communicative purposes, it will be very useful to discuss the theories of Emery (2000) and take up the observations of Kobayashi and Kohshima (2001) already introduced in §1.1. Primates have learned to live in increasingly large groups, where communication for the management of resources and hierarchies has become progressively more and more important. According to Emery (2000), this would have made visual cues more and more important. In support of this idea, the author brings first of all a morphological data: that is, only in primates the facial muscles are so developed and complex. This complexity allows for much greater expressiveness. Have you ever seen a dog frown? (No, the Bulldog does not count because forehead wrinkles are not obtained by contraction of the forehead muscles, but by an overabundance of skin). A second morphological datum that Emery (2000) brings to support his thesis concerns instead the conformation of the face of primates. In prosimians, compared to large anthropomorphic apes such as gorillas or chimpanzees, the snout appears

5.3

Social Structure and Body Structure Influence the Use of Indexical Cues

55

even more elongated, it is as if getting closer and closer to the genus homo the face had progressively flattened keeping some elements protruding highlights such as the nose or (in men) the eyebrows. This flattening of the face, usually accompanied by a shrinkage of the eyes (in relation to the general size of the face and the body of the primate), according to Emery, could have led to a greater communicative significance of individual facial features. The eyes, being smaller but more surrounded by muscles, have become more expressive and easier to interpret. The observations of Kobayashi and Kohshima (2001) are also extremely useful in explaining how the general physical conformation of the animal affects indexical communication. As already mentioned in §1.1, the two primatologists identified a correlation between the height at which the animal places its head when it walks and the portion of exposed sclera. The two primatologists explained this regularity in terms of energy expenditure: a wide sclera, which allows the iris to range comfortably in the eye, allows the animal to save considerable energy while focusing the visual scene through the fovea. In fact, primates, in order to focus, must place the object of interest at the center of their visual range; this operation is much less expensive if it involves only moving the irises rather than adjusting the whole head or even the whole body. In fact, macaques, capuchin capuchins, oedipus tamarins, ring-tailed lemurs, black lemurs and brown lemurs respond mainly to the direction of the head and of the whole body of the observed subject to co-orient their attention (Tomasello et al., 1998; Emery et al. 1997; Vick & Anderson, 2003; Neiworth et al., 2002; Shepherd & Platt, 2008; Ruiz et al., 2009). Whereas chimpanzees, bonobos, and orangutans appear to respond to both eye direction and head direction as half indexicals, but the observed subject’s head direction for them is the most salient indexical in a scene. Finally, for human children subjected to the same experiment, the eyes instead proved to be a more salient indication tool than the orientation of the head (Tomasello et al., 2007). All these data solidly confirm the hypothesis of Kobayahi and Kohshima. Actually, if it is true that in primates - as we will see - visual signals actually assume fundamental importance, nevertheless these are not a phylogenetic novelty introduced by primates: not only simple eye contact, but also the more complex geometric pursuit of the gaze is already present in reptiles (for example we have seen the red-legged tortoise) and in birds (crows). This observation does not make the role of gazes in primate communication less important, but it should certainly discourage the idea that the use of gazes for communication purposes is unique to primates. Primates are probably the animal family that most relies on looks to communicate, but not the only one. In the following pages we will observe the behavior of non-human primates in order to answer the following question: what role do eye contact and gaze tracking play in the communication of non-human primates?

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5.4

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What Does We Share with Other Animals?

Gaze Following in Non-human Primates

Lemurs, primates not directly related to humans, have been the subject of conflicting studies in this regard. In 1996 a Japanese scholar named Shoji Itakura, comparing eleven species of primates (including 3 brown lemurs, Lemur fulvus and 4 black lemurs, Lemur sciureus) found a low percentage of correct answers among lemurs in a target identification task through the gaze of a human experimenter. Indeed, in 1999 Anderson and Mitchelll experimentally showed that lemurs seem to lack the ability to co-orient their visual attention with others (Anderson & Mitchell, 1999). This study was conducted on a species called Eulemur macaco, years after a study conducted on two individuals of the same species and four Eulemur fulvus showed on the contrary that lemurs seem capable, not only of co-orienting their attention with their conspecifics, but also to use the other’s gaze as if it were an indexical (Ruiz et al., 2009). This finding was confirmed by other studies with the same lemur species and also with ring-tailed lemurs (Lemur catta) (Sandel et al., 2011; Shepherd & Platt, 2008). The Cebids (Cebidae) are a family of New World monkeys and usually have a very complex social structure. This feature in primates is often associated with a skillful use of eye communication. Despite this, early studies seemed to support the idea that cebids do not use the gaze of others much as a tool for information. In this regard, we cite once again the Itakura study of 1996. Of the 11 primate species compared, there were 10 specimens of squirrel monkeys (Saimiri sciureus), 3 specimens of pin monkeys (Cebus apella) and three specimens of capuchin monkeys (Cebus capucinus). While for pin monkeys and capuchin monkeys the experimenter found about 50% correct answers, for squirrel monkeys he found a low percentage of correct answers. However more recent studies conducted with more precise experimental procedures deny this first idea. In particular. In 2002 Neiworth and collaborators tested the visual co-orientation ability of oedipus tamarins (Saguinus oedipus) by detecting their ability to visually co-orient themselves with their own conspecifics, against the inability to follow the gaze of humans and use it as an indexical . In 2006 Judith Burkhart and Adolf Heschl conducted a series of experiments on the white-plumed marmoset (Callitgrix jacchus), which is a primate able to live in environments usually frequented by humans and which usually lives in small matriarchal groups of about 2–15 individuals. With a series of experiments the two researchers showed that these animals are able to follow the gaze of human experimenters. Intrigued by the abilities of these cebids, from which on the basis of the previous literature one might have expected lower abilities, the same experimenters published a new study the following year in which they demonstrated that the white-plumed marmosets are able to identify the direction in which a conspecific is glancing, but are unable to assume another individual’s visual perspective (e.g. inferring what he can or cannot see from his perspective) (Burkart & Heschl, 2007). Pin monkeys were then directly rescued in 2009, together with Geoffroy’s spider monkeys (Ateles geoffroyi) from a study conducted by Federica Amici and collaborators which showed, contrary to Itakura’s study, that these primates show a

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spontaneous gaze-chasing behavior of a human experimenter, in some cases even in the presence of physical barriers that partially obscure the vision. A very interesting species are the rhesus macaques (Macaca mulatta): they live in extremely complex social contexts, have a brain structurally similar to the human one and, like men, make extensive use of sight to convey social information (Machado & Bachevalier, 2003). It has long been known that the eyes exert a strong attraction in individuals of this species (Keating & Keating, 1982; McKelvie, 1976) and that it is possible to experimentally induce them to follow the gaze of conspecifics to find food (Tomasello et al., 1998). Rhesus macaques look into the eyes of their conspecifics to identify them (Gothard et al., 2009; Parr et al., 2000; Keating and Keating; McKelvie, 1976) and to understand the emotions they are feeling (Payne & Bachevalier, 2013; Gothard et al., 2004). They tend to look longer at the eyes of conspecifics turned towards them, rather than those turned away; moreover, the eyes are always the element looked at for the longest time in the face of the other, however if a conspecific is familiar to them, they look almost exclusively in the eyes, if it is not familiar they tend to look also at non salient elements of the face such as for example the ears (Leonard et al., 2012). But the looks between conspecifics are not suitable for all situations! After the resolution of a conflict, for example, the two contenders never look each other in the eye, according to Waal and Ren (1988) this happens because the subordinates are afraid of the dominants and therefore avoid looking at them. Rhesus macaques have another very important feature, apparently absent in other species closer to the genus homo such as orangutans and gorillas: they seem able to distinguish between what an individual (it has been demonstrated with a human experimenter) is looking at and what is not looking (Flombaum & Santos, 2005). The interesting thing is that, exactly as it happens for humans, also rhesus macaques, in the first weeks of life, show a very specific ocular behavior: from the moment they are born up to the first 8 weeks of life, attention for the eyes of other conspecifics increases; and then slowly decreases until 14–18 weeks of age, and then increases again (Wang et al., 2020). Furthermore, as for humans, in the very first stage of their life (about one month), rhesus macaques have a very intense emotional communication with their mother, in which a central component is the tendency to exchange prolonged and intense looks with her (Ferrari et al., 2009). Another common characteristic in the ontogenetic development of the macaque and man from this point of view has been shown in a group of nemestrine macaques (Macaca nemestrina) which, if, like men, in adulthood can follow each other’s gaze referring to the head/eyes orientation, and referring exclusively to the direction of the gaze, when young (2–6 years) however these animals appear unable to direct their visual attention only on the basis of the direction of the gaze of the other (Ferrari et al., 2000). This ontogenetic orientation suggests the existence of critical periods for the acquisition of some skills whose development depends on experience. For example, in 2008, the Japanese researcher Yochi Sugita raised some Japanese macaque (Macaca fuscata) cubs for 6, 12 and 24 months, depriving them of the vision of any face, human or animal. When, at the end of the deprivation period, the puppies

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were subjected to the usual visual orientation task, they always preferred the vision of faces to that of other objects; which is in line with the tendency of human infants to recognize and prefer face-like stimuli at birth. However, still in the same study, Sugita showed the role of experience for the concrete development of facial analysis. In fact, after evaluating the integrity of the face recognition ability, he exposed some puppies of his experiments to the continuous vision of human faces and others to the continuous vision of faces of conspecifics. In doing so, he obtained that the puppies that had been exposed to human faces had difficulty perceiving those of the conspecifics as faces and vice versa, the puppies exposed to the vision of the conspecifics’ faces reacted to human faces as to objects. According to the researcher, this means that puppies are born with the ability to recognize faces and consider them salient with respect to other stimuli; but experience then makes this mental prototype abstract, a very concrete configuration that orients the preference towards the most frequent facial configuration in the world experienced by the subject. Indeed, the ocular behavior of macaques shows frequent changes during ontogenetic development; for example, if at birth they seem to prefer the faces of conspecifics, in five weeks of life they tend to stare more at the faces of individuals of other species (Parr et al., 2016). Or, even more interesting, it is the development of social competence in the management of direct gazes or those directed elsewhere: in fact, if in the first two months of life an analogous and ever-increasing interest emerges in rhesus macaques for direct gazes and those directed elsewhere, at two months of age they tend to stare longer at gazes directed towards them, but with shorter periods of fixation; this means that they observe longer (probably to assess any dangers), but more warily (Muschinski et al., 2016). Around 5 and a half months of age they learn to follow the gaze of the other and only during a period analogous to human adolescence, in adulthood, they learn to integrate the information coming from the eyes with other social information available to them about the individual they are observing (Tomasello et al., 2001). Analogies in social behavior between the eyes of macaques and those of humans are also evident in adulthood: both humans and macaques tend to direct their attention in the direction of the eyes of the person they are looking at (Deaner & Platt, 2003; Emery et al. al. 1997). Interest in the eyes of conspecifics and the concomitant co-orientation of attention has also been experimentally demonstrated in other macaque species (M. arctoides, M. nemestrina) and in other vervet monkeys (Cercicebus Atys torquatus) (Tomasello et al., 1998). Macaques’ abilities to use gaze as a source of information have been extensively documented in various species. A peculiarity discovered in macaques that can be very useful for interpreting the frequent inconsistencies in the literature on gaze following in primates is that gaze tracking is not context-independent. For example, Grossens and co-workers in 2008 showed that dog macaques (Macaca fascicularis) follow the gaze of a human experimenter much more easily if the experimenter, after drawing the individual’s attention to his gaze, shows a strongly characterized expression emotionally rather than if he has an emotionally neutral face. Furthermore, in this case, the macaques also show what we have called the “double gaze”,

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that is, after looking at the target object, they go back to look at the gaze that indicated it to them. Among vervet monkeys, it is probably not only macaques that make extensive use of communication with the eyes. In 2004, the study by Scerif et al. conducted on six vervet monkeys (Cercioithecus diana) required the experimental subjects to follow the gaze of a conspecific portrayed in a photo and thus identify a target object. The results revealed that most of the specimens were able to co-orient their attention with the model towards the target, furthermore according to the experimenters this co-orientation also seemed to show the establishment of a relationship between the model and the agent. Like macaques, baboons also belong to the Cercopithecidae family, but they seem not to have the same propensity to attach importance to eye communication, although they have the competence. The social organization of the baboons changes from species to species but usually they live in mixed herds with several males and females or in polygamous groups with only one adult male, several females and the cubs. Groups are always managed with very strict hierarchies. Guinea baboons (Papio papio), or green baboons (Papio anubis) for example, do not spontaneously use the gaze of others to direct their attention, however they can learn to do so if this acquires a predictive value (Fagot & Deruelle, 2002; Vick & Anderson, 2003) or a competitive advantage (Parron & Meguerditchian, 2016) in their environment. In the latter case, they even tend to correct their spatial location in order to better follow the gaze of a human subject (ivi). Captive green baboons (albeit in groups of 16 individuals) stop communicating visually with their human partner if this is in a position where it would not be able to see its signals (Bourjade et al., 2014). Gibbons are another interesting genus of primates because they create families with monogamous and stable pairs and live in small groups normally made up of parents and offspring (on average two) (Kleiman, 1977). They are particularly interesting for our work because it is assumed that a less complex and chaotic social context can correspond to a lower development of communication skills. In 2004, a Japanese research team showed that a white-handed gibbon (Hylobates lar) lived in captivity and accustomed to the presence of man since childhood, was able to use the gaze of a human experimenter as an index sign (Inoue et al., 2004). A few years later, the same proficiency was found in a group of captive capted gibbons (Hylobates pileatus) (Horton and Caldwell 2006). More recently, the issue has been addressed with a more rigorous experimental methodology and a larger group of gibbons of different species: ten Siamangs (Symphalangus syndactylus), eight caped gibbons, four gray gibbons (H. moloch) and two handed gibbons whites from different European zoos. The procedure was quite complex and we will not describe it here in detail, but we will limit ourselves to saying that the experimenters concluded that gibbons actually have the ability to co-orient their visual attention together with other individuals based on their gaze however - unlike other primates as we will see they do not seem able to take on the visual perspective of other individuals (geometrical gaze following) (Liebal & Kaminski, 2012). Let’s take one more small phylogenetic step towards the genus homo and let’s consider the behavior of orangutans. Although the social behavior of this genus of

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primates varies from species to species, on average it can be said that they live in very small groups, but that they have the habit of socializing in larger groups around fruit trees, especially in periods when the food is lacking. In general, the male adults defend large territories which overlap with smaller territories defended by female adults and in which the cubs also live. Males usually do not gang up on territorial defense, and females also have competitive relationships with each other. The male puppies, once grown, leave the territory, the females too but usually they go to stay in a territory adjacent to that of the mother. Orangutans are generally calm, not very dramatic in their emotional expressions, and reserved (Parker & Mitchell, 1999). Even in orangutans, mutual gazes have a social function, although less salient than in other primates. Call and Tomasello (1994) were the first to demonstrate with two Bornean orangutans (Pongo pygmaeus), that if properly trained these animals are able to consider gazes as an indexical gesture. This result was replicated a few years later by the same group of researchers with a slightly larger number of subjects, 6 (Bräuer et al., 2005); again a few years later with 7 other orangutans (Pitman & Shumaker, 2009) and finally in 2014 with 7 other orangutans (Kano & Call, 2014). However, this is in contrast with what was found by Okamoto-Barth et al. (2007), who in a visual obstruction task during gaze following conducted, among others, on 5 orangutans, found few signals that these animals are able to follow the visual perspective of others. To unravel the question, however, it must be emphasized that this ability could be spontaneously absent, but potential in orangutans, probably because, even if they normally observe the face of other individuals (conspecific and not) in a similar way to other primates (Kano et al., 2012), naturally tend to avoid the direct gaze of other individuals and this is probably the reason that drives them to avoid looking the experimenter in the eye (Mulcahy & Suddendorf, 2011). Pitman and Shumaker (2009) have also experimentally found that the educational style with which the primate was raised makes no difference in its ability to develop the ability to follow the gaze of the other, as it is resilient even in not very responsive educational contexts. Studying a rather large group of Bornean orangutans in semi-freedom, Kaplan and Rogers (2002) observed that orangutans tend to avoid direct gazes more than humans or great apes, preferring a peripheral observation of each other’s gaze. According to the researchers, this is probably linked to the type of social life led by these primates: their very solitary habit is hyper-stimulated by the overcrowding that is created around the fruit trees and to compensate the animals avoid the gaze of others. However, as with other primate genera, eye behavior at fruit tree gatherings varied with age. Specifically, young people were the ones who spent more time observing the gaze of others; their gazes were not returned by either adults or puppies. The youngsters looked at the other youngsters with many glances but all for a short time, instead they looked at the puppies for a very long time. There was also a difference in what the young people observed: when they looked at other young people, they mostly explored their faces; when, on the other hand, they observed the adults, half of the time was dedicated to the exploration of the face and above all of the eyes, the other half instead was dedicated to the limbs. In any case Kaplan and Rogers specify that communication with gazes in orangutans can be

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further influenced by the level of social cohesion of the group to which they belong, in the sense that it develops more in more cohesive groups.

5.4.1

Hippies Versus Warmongers

It remains for us to discuss the way in which the two species closest to us use their gaze; these are two species in some respects completely antithetical, but equally related to us: the bonobos and the chimpanzees, the two ancestors absolutely closest to us, which separated phylogenetically very recently, only 1.2 million years ago (Prüfer et al., 2012). In these two species, sociality differs enormously: bonobos appear to be almost completely peaceful; scientific and popular literature often describe them by comparing them to flower children, groups that demonstrate with their example the possibility of an existence without violence well represented by the slogan “brothers let’s make love, let’s not make war”. In contrast, chimpanzees are extremely violent in temper; they often engage in bloody fights and practice macabre killings of annoying conspecifics in ways that could even appear almost rich in grim symbolism, for example by detaching their testicles with their hands. If in male chimpanzees the defense of social rank is the object of fierce disputes and power struggles within the same group can even lead to the death of some individuals, bonobos do not appear equally interested in the question: they do not fight for social ranks and hierarchies and use various forms of sexual interactions to manage social relationships. If chimpanzees usually mount their sexual partner from behind, bonobos prefer intercourse that allows them to look at each other’s faces. If chimpanzee females are sexually receptive only during the periods in which it is possible for them to become pregnant, bonobo females continue to be so even during pregnancy and while breastfeeding, when intercourse would in no case lead to conception. And after all, in chimpanzees the females are normally subordinate to the males and do not maintain special relationships between them, while in the bonobos the relationship between male and female is egalitarian or even in some cases the female is considered of superior rank and the females create a group cohesive and that, in case of attempts by males to attack a female, they defend each other and cooperatively (Furuichi 2019). Strong differences are also found in the social dynamics between groups. Rival groups of chimpanzees often go as far as killing members of the opposing group, sometimes until one group completely eliminates the other by killing the males and absorbing the females into itself. On the contrary, the bonobos sometimes merge for a few days with the rival groups, sharing the food; in extreme cases they may turn to intimidating behavior, but never outright violence. Offspring of female chimpanzees that move from one group to another are often killed and cannibalized by the other males in the landing group; among bonobos, on the other hand, such behavior is highly improbable, probably impossible (ivi). Kano et al. (2015) wondered if these differences in social behavior could not be at the basis of different patterns of behavior in looking for the eyes of the other,

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hypothesizing that more egalitarian and tolerant social systems could correspond to a tendency to look more for the gaze of others individuals. To test their hypothesis, they compared 14 bonobos (Pan paniscus) and 20 chimpanzees (Pan troglodytes) in a task of observing other individuals of both species using the eye tracker. Using this methodology, they found that although the two species appear to behave more or less in a similar way, mainly observing the faces and eyes of the models, there was a significant interspecific difference: the bonobos tended to look more than the chimpanzees at the eyes and the face in general, while chimpanzees, compared to bonobos, looked more at the object that the individual was holding, his mouth and his genitals. According to the authors, there could be a common neural, hormonal and genetic mechanism underlying the differences in the ocular behavior of the two species. Specifically, oxytocin is the affiliative hormone par excellence: of fundamental importance during childbirth and breastfeeding, it is also the hormone that mediates affective relationships of all kinds ranging from friendship, mating, paternity. Oxytocin production did not change between the two species (Hopkins et al., 2015), however the oxytocin receptor genes differ in the two species (Staes et al., 2014). Normally intranasal injections of oxytocin push a subject to look at the eyes of others longer, this has been demonstrated in men (Andari et al., 2010); in dogs (Nagasawa et al., 2015); in Barbary Macaques (Kotani et al., 2017) and macaques (Dal Monte et al., 2014). A recently conducted study compared bonobos and chimpanzees in a task of observing images of other bonobos and chimpanzees with the eye tracker and after administration of oxytocin. The result was that while the bonobos looked longer into the model’s eyes than in the control condition, the chimpanzees behaved differently. Out of six chimpanzees tested, one behaved like the bonobos by observing the model’s eyes longer, while the other five observed the model’s mouth longer. This behavior was interpreted by the experimenters as partial gaze avoidance (Brooks et al., 2021). The oxytonergic system could be at the basis of the differences found between these two species, however it is very difficult, with today’s knowledge, to establish with certainty the reason for this difference; however, it should be noted that although chimpanzees outperform bonobos in tasks that require the use of tools and an understanding of physical causality, bonobos outperform chimpanzees in tasks of gaze following and hence understanding of the intention of an agent (Herrmann et al., 2010; Tomasello et al., 2007). In any case, the fact that both species are able to use the gaze of other individuals as an indexical and to do so beyond physical barriers is now quite commonly accepted in the scientific literature (Bräuer et al., 2005; Povinelli & Eddy, 1996a; Okamoto-Barth et al. (2007). The greater sensitivity of bonobos to the gaze of others compared to chimpanzees is also manifested in the fact that, while bonobos seem attracted both by the gaze of their conspecifics and by that of individuals of other species, chimpanzees do not always respond to human gazes and those of other species in general (Kano & Call, 2014). Bonobos are more attracted to human gaze than chimpanzees (Mulholland et al., 2020). And curiously, in 2007 two experimenters tricked two chimpanzees into collaborating to obtain a common object of desire, but despite their success, the two

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animals did not look each other in the eye in any of their attempts to collaborate to achieve a common goal (Hirata & Fuwa, 2007). Scientific literature usually attributes great intelligence to chimpanzees. Already the classic study by Itakura in 1996 which compared 11 species (and which we talked about in the previous paragraphs) showed a greater ability of chimpanzees, compared to other primates, to infer the reference object exclusively on the basis of gaze monitoring of the human experimenter. Although it is not clear whether all the primates that follow the gazes of others follow the own direction of the eyes or in general the orientation of the head and body of whoever emits the signal, for chimpanzees instead their tendency to follow even eye direction only (Bethell et al., 2007). Chimpanzees follow the gaze of others even if the direction of the gaze is partially occluded by physical impediments and they do so following a geometric completion structure (Tomasello et al., 1999). The fierce hierarchical rules of their complex social groups can be partially circumvented by subordinate individuals thanks to their ability to understand where a dominant individual is looking and therefore not looking (Hare et al., 2000, 2001, 2006). But chimpanzees can go even further: our astute cousins can condition to their advantage, in particular contexts, such as in a context of competition for food, the mental state of the other, by manipulating the possibility of being seen or heard or not (Hare et al., 2006; Melis et al., 2006). Chimpanzees are able to follow the gaze of a conspecific to obtain information on the environment of interest to them (Hall et al., 2014) and are even able to understand that another individual is exploiting the direction of their own gaze to infer information on the environment (Hall et al., 2017). In particular contexts that allow them to access food through understanding the attentional state of a human experimenter, chimpanzees are attracted to the latter’s eyes (Povinelli & Eddy, 1996b). They do not attribute their baggage of personal experiences to those of the subject whose gaze they are pursuing (Karg et al., 2015). Chimpanzees are even able to make inferences about the intentional state of a human experimenter in the light of the memory of what they saw him look at in a previous experience, i.e. they are able to retain in memory what was the object of the experimenter’s visual attention and use this memory to make inferences about his emotional reactions. This ability has also been found in bonobos, but in chimpanzees it is more flexible, i.e. it manifests itself in multiple contexts (MacLean & Hare, 2012). However, it should be emphasized that these incredible talents of chimpanzees in the use of eye signals are certainly influenced by the fact that in most cases the studies on these animals are conducted with specimens living in captivity in close contact with humans and that it is not difficult to hypothesize that their performance in the wild is different. As proof of this, the difference between the results of the same experiment conducted on two colonies of chimpanzees differently accustomed to contact with humans which led to different results in a task which required the animal to understand the relationship between visual attention of a human experimenter and his state of knowledge about the situation. If the colony of the experiment of Bulloch et al. (2008), more accustomed to human stimulations, was able to carry out the task, in the original experiment conducted by Reaux et al. (1999) and Povinelli et al. (1999) the data were very different. The reason, according to Bulloch and

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collaborators, would be precisely the different habituation to man by the participating groups of chimpanzees. Indeed, in a series of experiments, Kano et al. (2018) showed that the domestication effect can actually make a substantial difference in the development of the ability to infer the intentional state of the agent, making dogs and children superior to chimpanzees and even bonobos in this regard. If chimpanzees and bonobos in fact tend to follow the gaze of others simply following any event that has attracted their attention to whoever is emitting the signal (the fact that he has a colored object in his hand, that he is eating, that he calls them to name, who looks them in the eye. . . .), children and domesticated dogs, as we have seen in §4.1, do so only following an openly ostensive gesture. But the relationship with man is not the only factor that influences the interest of animals in the gaze of others. As we have seen, chimpanzees are perfectly capable of identifying the direction in which a human being is looking; however this ability is greatly reduced if the face is shot in a three-quarter perspective (Tomonaga & Imura, 2010). This probably happens precisely because the salient element that initiates the pursuit of the gaze is eye contact with the other (Tomonaga & Imura, 2015). And in fact, like humans, chimpanzees are particularly good at identifying the face of another chimpanzee among a series of other objects, but this does not happen if the face, instead of being captured in a frontal perspective, is captured from profile (ibid.). There are several similarities in eye behavior between chimpanzees and humans during the developmental age. As in humans and macaques, a slow development of eye communication skills can also be observed in chimpanzees: gaze tracking in these primates begins approximately between the third and fourth year of life (at least towards human experimenters) and only in adulthood do they learn to integrate it with their more general socio-cognitive skills and to use it in a flexible way, for example by ignoring the gaze of unreliable subjects (Tomasello et al., 2001). As chimpanzees age, the tendency to follow the gaze of others tends to decline somewhat (Lacreuse et al., 2014). As we have seen in newborns of men, even chimpanzee cubs prefer to look at individuals who look them straight in the eye, rather than individuals looking away (Myowa-Yamakoshi et al., 2003). Moreover, as often found also in men, in chimpanzees there is a very strong exchange of glances between mother and cub, the phenomenon has been observed both in wild groups (Van Lawick-Goodall, 1968) and in captive groups (Bard, 1994); but despite the omnipresence of the phenomenon, it is also subject to cultural influences in chimpanzees: in 2005 Bard and collaborators compared the dyads of chimpanzee mothers and children of two colonies that lived in captivity, one in America, the other in Japan. The Japanese colony exhibited a much higher number of changing gazes between mother and child than the American colony. Furthermore, since the time spent by the couple in mutual gazes was inversely proportional to the time the mother spent cradling the puppy, the researchers hypothesized that there was an inversely proportional relationship between gaze and physical contact. As we will see in the next chapter, in men it seems more plausible that this inversely proportional relationship is between physical contact and vocalizations (Matsuzawa, 2006).

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In bonobos, eye contact undoubtedly takes on a very strong meaning. For example, much social cohesion is maintained through same-sex relationships between females. These occur above all between females who do not have such strong ties as to practice constant and reciprocal grooming. Usually, a longer duration of these sexual intercourse is considered an indication of their greater success: well, recently a study has shown that if during these intercourse females exchange frequent mutual glances, these last longer (Annicchiarico et al., 2020). And in any case, before the copulatory act, the mutual looks between the future sexual partners become very frequent (Savage-Rumbaugh & Wilkerson, 1978). In spite of these differences, the predominantly cooperative value of eye-gazing is demonstrated by the fact that both bonobos and chimpanzees are better at using an experimenter’s gaze as an indexical gesture in cooperative contexts rather than in competitive contexts (MacLean & Hare, 2015). Furthermore, if until the first decade of the twenty-first century it was believed that none of the non-human primates was able to participate in triadic interactions (Tomonaga et al., 2004; Tomasello et al., 2005), a recent empirical study has changed the perspective on the question. MacLean and Hare (2013) in fact observed the spontaneous behavior of a total of 119 bonobos and chimpanzees in five different experimental contexts that allowed the animal the possibility of choosing whether or not to participate in triadic interactions. For example, they gave them the choice of interacting with a human and a toy rather than playing alone with the toy. With this methodology they found the presence of a motivation to interact with objects together with other partners rather than alone. This study is conducted with a more ecological methodology than the previous ones and is confirmed by another study from the 1990s (Russell et al., 1997) which reported the ability of some chimpanzee cubs to indicate an object to a human partner for social purposes and without any imperative on the part of the latter. According to Bard (2017), the differences found on this front by the various empirical studies can be attributed to the different experiences that the study subjects have with men: those more accustomed to contact with men are more likely to maintain triadic relationships with them. Given that, as we have seen, culture plays a fundamental role in regulating the communicative behavior of the eyes, we could conclude that chimpanzees and bonobos can participate in triadic interactions in which two subjects communicate about a third object or communication subject. However, it is not known to date whether this behavior is present or not in naturalistic contexts.

5.5

Double Gazes Are Not a Human Uniqueness

All these studies clearly show that communication with the eyes varies greatly from species to species and that it is influenced by social factors such as the complexity of the social structure of the species; by ecological factors such as whether the animal lives in captivity or in the wild; by cultural factors and also by genetic factors, such

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Table 5.1 Potential in the use of gaze for communicative purposes in the families of non-human primates Family Lemurs Cebids Vervet monkeys Gibbons Orangutans Gorilla Bonobos Chimpanzees

Reflex gaze • • • • • • •

Geometrical gaze • • •

Double gaze

•

• • • •

• •

as for example those that regulate the anatomical structure of the eye and of the facial expressions and perhaps also those that regulate the oxytonergic system of the species. As can also be seen from Table 5.1, the double gaze, which allows the triadic relationships which according to Tomasello would be the conditio sine qua non for the development of shared attention, are not a human uniqueness. Indeed, not only bonobos and chimpanzees, but even macaques - farthest from man from a phylogenetic point of view - seem able to use the double gaze. In our opinion, the review of studies analyzed in this chapter clearly shows that man is the animal that most spontaneously and most frequently uses his gaze for communicative purposes; perhaps it is also the animal that manages to derive the greatest advantages in terms of communication from this. However, evidently the use of the gaze for communicative purposes, even if we speak of a double gaze, is not his only prerogative. Probably the use of the double gaze is particularly useful in humans because it facilitates the acquisition of the first words and in general the Theory of Mind. But the Theory of Mind, as it is now widely established by the scientific literature (Milligan et al., 2007), is closely linked to language. That is, in the ontogenetic development it becomes more and more precise as the linguistic quotient (and not necessarily the cognitive one) of the child increases. It would therefore not be so strange to hypothesize that even on a phylogenetic level, a wise use of gazes for reading the mind of the other had become a current practice of the species thanks to the fact that language facilitates what Tomasello calls “intentional recursion”. In other words, it would seem more plausible to reverse the order of causality proposed by Tomasello. Tomasello believes that human beings have developed language thanks to the fact that we are a species particularly suited to intraspecific cooperation. The reason for this super-talent would in turn be found in man’s unique ability, according to Tomasello, to share intentionality with other individuals. Our theoretical proposal instead inverts the factors of causality: we believe that, on the contrary, if we are good at synchronizing ourselves for cooperative purposes and we are accustomed to shared intentionality it is thanks to the fact that we have developed language.

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The fact that behaviors such as the “double gaze” are present among non-human primates, at least at the level of potential of the species, but that actually this is not used so much, indicates that this type of intentionality is not only not indispensable to survival, but basically not so useful for these species. The reason why shared intentionality is not all that useful among nonhuman primates is that it is not recursive in them. What Tomasello calls “intentional recursion” is nothing other than linguistic recursion applied to the Theory of Mind. In the absence of the recursive component, shared intentionality becomes almost completely useless and therefore is not used by our cousins who do not have great recursive potential.

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Chapter 6

Why Gazes Are Not So Special

6.1

A Special Breath and a Special Vocal Tract

The eyes are not the only major morphological difference between humans and other primates; most of the differences are from the neck up: the large brain, the smaller anterior teeth, the protruding nose are distinctive features of humans (Lieberman, 2011). This extreme evolvability of the head is probably linked to the extreme modularity that it has assumed in primates or rather they are made up of relatively independent “pieces” of their growth and then integrated by the connecting structures. In fact, modularity and integration tend to favor evolutionary complexity in phylogeny (Wagner, 1996; Gerhart & Kirschner, 1997; Gilbert & Bolker, 2000). In the theories discussed in Chap. 3, ample space is given to the development of the human eye, but little weight is given to the evolution of the structures of the supralringeal vocal tract. Strange choice given that they are associated with two fundamental functions, that is breathing and nutrition, and with a secondary function, but of very high adaptive value and without which we would probably have already become extinct, that is language. There are numerous open questions regarding the phylogenetic origin of language: what makes the question particularly intricate is not only the intrinsic complexity of the structure that allows us to articulate language, but precisely the fact that the linguistic function is a “parasite” of a vital function: breathing. Furthermore, the respiratory system shares part of the anatomical structures with the digestive system. The Aristotelian metaphor that ontologically defines language as the breathing of the soul (Lo Piparo, 2003) to emphasize its pervasive importance in the structuring of thought (without, of course, diminishing the communicative one) assumes a strong ambivalence from this point of view. It is probably no coincidence that human breathing has unique characteristics compared to the rest of the animal kingdom. But what are these characteristics? Briefly we can say that the most important are: a nose outside the muzzle; the non-intranarial larynx; the inability to open the trachea beyond 50% of its opening; © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Pennisi, Gazes, Words, and Silences in Pragmatics, Perspectives in Pragmatics, Philosophy & Psychology 36, https://doi.org/10.1007/978-3-031-42571-4_6

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chimpanzee teeth lips

human nasal cavity

tongue

mandible hyoid bone

hard palate velum uvula epiglottis

Why Gazes Are Not So Special

nasal cavity

tongue

larynx vocal chords oesophagus trachea

Fig. 6.1 A comparison of the direction of air flow when entering the nose of chimpanzee and human

the absence of air chambers; the absence of the expanded body in the hyoid bone and finally a smaller and rounded tongue than that of other primates. In the following pages, all these features will be explained in detail. As we have seen in §4.3 Emery (2000) had noticed in primates a progressive flattening of the muzzle as we approach the genus homo, at the same time there was also a shrinking of the eyes (in proportion to the size of the animal). In humans, the muzzle practically disappears, but the prominent nose remains. The presence of the external nose is a unique feature of the genus Homo (Lieberman, 2011) and appears to have appeared about two million years ago in the first Homo, simultaneously with the disappearance of the snout. Nasal breathing favors a better exchange of humidity and heat between inside and outside and the prominent external nose is more effective than the internal one in this operation; therefore it is likely that natural selection has favored, through the action on the morphology of the nose, an optimization of the humidification of the inhaled air and dehumidification of the exhaled air during aerobic exercise, allowing our ancestors to increase their physical resistance in the heat (Franciscus & Trinkaus, 1988). However, whenever a human being is subjected to intense physical exertion, he switches to forced oral breathing because the efficiency in the humidification and dehumidification process comes at the price of greater air resistance due to the increased turbulence at to which it is subjected; so by breathing through the mouth it is possible to increase the volume of the air entering and also the obligation to pass during physical exertion (not after to recover) to oral breathing seems to be an exclusively human characteristic (Bramble & Lieberman, 2004). In Fig. 6.1 you can see a comparison between the air flow trajectoris in humans and non-humans

6.1

A Special Breath and a Special Vocal Tract

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primates. The interesting thing is that the air resistance that the individual (not the species) encounters during growth affects the development of the nasal cavities: children, for example, born with enlarged adenoids and therefore forced to breathe through the mouth, tend to have a less growth of the nose (because it does not undergo the usual pressure of the incoming air); however, after surgical removal of the adenoids, the growth of the nose normalizes (Zucconi et al., 1993). Similar data can also be found in relation to the possibility of growth of the oral cavity: those born with very narrow nasal cavities often tend to develop somewhat higher and deeper oral cavities (Brattstrom et al., 1991). According to Liebereman, the trends in the morphology of the noses of many populations can be plausibly explained by placing these mechanisms in relation to the climate in which they have settled (Lieberman, 2011). These examples show us how a primary function such as breathing appears to be easy to change; the principle is that if the environmental conditions require an adaptation to one of the primary functions, the evolution or extinction mechanism works even more ferociously. It should not be forgotten that language, as we have already said, is grafted onto the primary structures of respiration, a function that - as we have seen - is able to condition the change of structures already at the ontogenetic level. When we speak, our respiratory organs orient the air that comes out of the lungs in different ways, generating that phonological complexity that is transformed into language. The possibility of emitting different types of phones is therefore linked to the extreme ability to modulate the air flow. The air that comes out of the lungs through the trachea reaches the larynx. The larynx is that part of the human respiratory system that is between the trachea (bottom) and the pharynx (top) and in humans it is exceptionally low. In part, bipedalism explains the exceptional baseness of the human larynx as a tool for optimizing functions that require a certain slope such as swallowing, breathing; but the real reason for this extreme baseness is not yet fully clarified, it is certain that this baseness favors vocalization. And in fact the larynx is indispensable for the production of articulated language. In other mammals, the air can range from the nasopharynx (part of the pharynx that extends to the height of the nose) to the trachea without any obstacle within a channel specifically dedicated to breathing. The epiglottis, the gateway to the larynx, is in fact already located in the nasopharynx; this type of arrangement is called the intranarial larynx. The advantage of this type of configuration is that it is very difficult for liquids or food to end up in the larynx, putting the animal at risk of suffocation. In the adult human being, however, the larynx does not have an intranarial configuration, and in fact suffocation is a very common phenomenon (Lieberman, 2011). The larynx is made up of a series of muscles, cartilages and ligaments that modulate the flow of air. When we make an extreme effort, such as lifting a weight, we seal the trachea by preventing air from escaping through the larynx. When we cough, we seal the trachea again through the larynx to increase the air pressure and then open it abruptly, favoring the expulsion of something unwanted above the

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larynx. But usually, the larynx remains open to let the air pass and modulates its flow. The phonation muscles operate mostly in two ways: by stretching and relaxing the vocal cords with a tilting movement obtained through the oscillation of the thyroid gland due to the movement of the cricothyroid muscle. This movement participates in the production of high-pitched sounds. The other laryngeal movement responsible for phonation is the opening and closing of the glottis, which brings the vocal folds closer to and away from the sagittal plane. In particular, a muscle, called arytenoid, contributes to this latter process, which in humans and monkeys is particularly short and is responsible for a peculiarity in our breathing: its action allows for an extraordinary speed and efficiency of the process of opening and closing the glottis, but limits its maximum opening to about half the cross-sectional area of the trachea. The speed of the process is transformed into the brevity of the process. In most other mammals, however, the vocal processes are slower and the tracheal opening also reaches 67–75% of the tracheal section; in some, such as horses for example, even much more (Lieberman, 2011). The length of this process favors the maximization of air flow and this translates into a greater ability of the animal to gain speed in a short time, but make vocalization more difficult. And in fact, we humans are skilled vocalizers, but the bursts of speed during aerobic activity are undoubtedly not our talent. Conversely, among mammals we are the best in running for longest routes: the low speeds do not require an instantaneous consumption of very high oxygen. Daniel Lieberman (2011) hypothesized that the inability to transversely open the trachea with the same amplitude as other mammals, inherited from monkeys, having inhibited the power of the sprint has, by compensation, pushed the homo genus to improve in aerobic endurance. Another peculiarity of the human supralaryngeal vocal tract is the lack of air chambers. The air chambers are tanks that the animal can inflate with air as needed, exhaling while keeping the mouth and nose closed. They are present in most primates and in many vertebrates, although in different positions. In monkeys they are usually found bilaterally with respect to the mucous membrane in the laryngopharynx, while in gorillas and chimpanzees they are found under the hyoid bone and then fork extending to the armpits. Fitch and Hauser (2003) hypothesized that these can act as a sounding board to make the emitter’s body appear larger and thus inhibit any opponents. This idea appears quite credible: just think of the classic vision of the gorilla beating its chest after inflating its air chambers. In the upper part of the larynx is the hyoid bone. The root of the tongue is attached to the hyoid bone. While we speak or swallow, the hyoid bone changes position, especially depending on the tongue and jaw. Compared to other primates, the hyoid bone lacks an expanded body. In humans, the tongue is particularly small and rounded and according to Lieberman’s (2011) reconstruction this shape of the tongue, combined with the erect neck and the lack of a muzzle, have caused the larynx to sag. Assuming various possible scenarios on the concatenation of events, the Harvard paleoanthropologist speculatively came to the conclusion that bipedalism alone cannot by itself have caused that unique laryngeal lowering of man and responsible for the ability to pronounce articulated sounds; along with bipedalism,

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All Sensory Pathways Lead to Mom, but Hearing Is the Fastest

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the shrinking of the face must have occurred first. The question then becomes, what caused the shrinking of the face? And the three most plausible answers are the development of smaller teeth linked to dietary changes; the development of a prominent external nose or the ability to produce articulate sounds. The considerations on the importance that the eye may have had in the development of empathy and intersubjective communication are certainly helpful in understanding how the eye could facilitate these dynamics. However, while for the whitening of the ocular sclera and for the possibility of moving the eyes a lot in the horizontal plane, the Baconian principle of the simplest choice would force us to consider that this particular morphological conformation is less expensive than that of other primates in terms of energy, with regard to the changes in the supralaryngeal vocal tract, one should be able to explain what could justify, Darwinian speaking, the development of a characteristic so dangerous for the survival of the individual (and of the species), namely the non-intranarial larynx. In other words, it is implausible that the eye has developed such a conformation to facilitate communication, since there is an even more adaptive reason to justify this change: it costs less in terms of energy. Likely communication facilitation is a pleasant side effect of this energy saving. The same cannot be said of the development of a non-intranarial larynx: it has a very high cost in terms of the possibility of survival and therefore must have been associated with a very strong advantage; probably, the language. It is therefore perhaps more effective that an explanation of the phylogenetic path that led from monkeys to the genus homo accounts for otherwise inexplicable phenomena such as the lowering of the larynx, rather than phenomena that can be understood more simply in terms of energy saving.

6.2

All Sensory Pathways Lead to Mom, but Hearing Is the Fastest

Undoubtedly, given that it is ready and available for use, word-acquiring children use eye reference to disambiguate the meaning of those strange, well-structured vocalizations they hear in adults. However, we must reflect on an objective fact: it is true that the interest in the eyes begins at birth; it is rooted in subcortical structures and during growth it also involves cortical structures, thus allowing increasingly complex cognitive and mentalistic performances, also thanks to the growing empathic involvement it allows. However, it is equally true that hearing (like touch for that matter) is active well before sight, already in utero. In response to auditory cues the baby in the womb immediately begins to respond to the mother’s stimuli in a different way than it does to other stimuli. Specifically, for example, already between the twenty-first and thirty-third week the infant’s heart rate increases in response to the mother’s voice and decreases in response to that of another woman (Kisilevsky et al., 2003). Between the thirty-third and forty-first

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week of gestation, the infant’s heartbeat responds in a peculiar way to the mother tongue and not to different languages (Kisilevsky et al., 2009); this same study also confirms the uniqueness of the infant’s response in utero to the mother’s voice rather than to other voices. One might think that this depends on the fact that the mother’s voice comes from inside and not from outside the body in which the baby is immersed, however the phenomenon has been found between the thirty-third and thirty-seventh week of gestation with linguistic inputs from the mother or another unrelated woman recorded and played to the baby in both cases from outside the belly (DeCasper et al., 1994). Hearing the mother’s voice is the first step in building the bond between mother and baby. Furthermore, just as the eyes immediately take on the character of a special stimulus in the eyes of the newborn (§1.1), also language takes on a specific character for them. For example, Pena et al. (2003) showed with optical topography that newborns respond with activation of the left hemisphere when hearing a linguistic input and of the right hemisphere when hearing the same input but replicated in reverse. The perinatal period, in fact, is the one in which the greatest number of sensory, motor and associative synapses accumulate in the cortical areas. Furthermore, in a series of experiments that seem to leave little room for alternative interpretations, Sai (2005) demonstrated that recognition of the mother’s face at birth depends on prenatal exposure to her voice. When this auditory input is missing, face recognition is delayed. Another fact that supports the idea that linguistic inputs are more important than visual ones in the development of social cognition is that autism, a neurodevelopmental disorder characterized (among other things) by deficits and anomalies of various types in the development of cognition (American Psychiatric Association, and D. S.,, and American Psychiatric Association, 2013) is much more frequent in children with deafness or hearing impairment than in children with blindness or vision impairment (Bougeard et al., 2021). The mutual attachment of mother and child is a fundamental mechanism for the survival of the child, and therefore of the species. Such an important mechanism is not entrusted only to a cognitive or perceptive possibility, on the contrary it becomes redundant in the brain. The mother’s auditory experience ontogenetically precedes the visual one; but of course, in case of deprivation, the child will use the visual experience (and also tactile, olfactory, gustatory) to recognize and bond with the mother. Indeed, sometimes there is some attachment problem between mother and child affected by congenital deafness (Leigh et al., 2004); however, normally hearing loss does not in itself preclude the child from developing a social life similar to that of others. These forms of compensation are also present in non-human animals. In § 4.4 we talked about the experiment conducted in 2008 by Sugita with Japanese macaques, the researcher deprived the macaques from birth of the possibility of seeing both human and animal faces, they were fed by a hooded experimenter. As we have seen, in this species mutual gazes are used in a very similar way to humans: that is, close exchanges of gazes between mother and child and use of the gaze as an indexical.

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All Sensory Pathways Lead to Mom, but Hearing Is the Fastest

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Despite this, the macaques raised in this way developed normal communication skills and forms. Although it is plausible that social cognition develops following similar average patterns, it is also likely that in each individual these follow different patterns, based on his or her particular characteristics. Let’s take an example to clarify the concept. Towards the end of the 1980s, many linguists became interested in the phenomenon of baby talk, i.e. that way of speaking to children typically used by adults which provides for sharper sounds, better scanning of sounds, greater slowness in the articulation of linguistic signs, particularly expressive body language, playful nudging, giggles and tickles. This way of addressing children (from birth up to about 3 years of age, with particular persistence between 3 and 5 months, Stern et al., 1983) is a cultural universal and according to the anthropologist Dean Falk it has both an emotional and a linguistic function: it facilitates synchronization between the two communicative partners and at the same time the transmission of information and language learning (Falk, 2011). It is a tool of great importance during language learning, and for the purposes of our discussion on involuntary cognitive compensations (of the caregivers and of the child himself) oriented towards the development of the child’s social cognition; well, even mothers who talk to their baby in sign language use a signed form of baby talk (Masataka, 1996), indicating how social cognition seems to adapt to the perceptive tools at its disposal. Social cognition, strictly chronologically speaking, begins with touch and hearing because these are the senses with which the infant first experiences the mother. Once born, hearing will remain the more used of the two. Even the exchange of visual signals with the mother, which arises with her identification, starts with the first crossing between her sight and her auditory recognition. Naturally, hearing is neither the irreplaceable nor the only sensory gateway to access social cognition, since the latter, being too important for the survival of the species, is built on the sensory support it finds available: if they are all available, they will all be used; in the absence of one of them, such as hearing for example, the other sensory doors will also give access to social cognition. If the primacy of hearing over sight in the construction of the mother/child relationship is emphasized here, it is to contest the idea that the development of social cognition as we know it necessarily needed the very close exchange of glances between mother and child which only white-sclera eyes would allow. The attachment between mother and child is certainly strong in the human species, but this is not linked to the whiteness of our sclera, but to the fact that man as Terrace himself explains - is more in need of parental care for survival than other animals. This greater need manifests itself both in a greater need for care at birth, as the human infant has fewer skills than any other infant in the animal kingdom; and in a more prolonged need for parental care after birth in relation to the length of life. Mothers must be strongly motivated to keep their young alive and therefore empathy and attachment between the two are certainly fundamental mechanisms for the survival of the species. However, if hearing is the sign that accompanies the baby’s perceptions from inside the mother’s womb to the outside, it is unlikely that the baby does not play a very strong role in the creation of this bond. We have therefore tried to show in this paragraph that the mother-child bond in the human

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species is too important a mechanism for the survival of the species to be mostly entrusted to a single mechanism, such as that of the possibility of exchanging glances in a face-to-face position between mother and child. The empathetic bond between mother and child passes through the sensory channels it finds available; can naturally develop different characteristics as a function of this, however in the absence of the possibility of exchanging glances with their mother, children can learn to speak by exploiting the strength of other sensory channels, as demonstrated by the fact that congenitally deaf children can develop the language quietly.

6.3

Loving Gazes Even among Other Primates

According to Terrace, the child develops a sense of self and of the other thanks to his ability to synchronize emotionally with his mother through the visual analysis of her emotional expressions. But this perspective has several problems. One implication of this idea in the first place is that congenitally blind people cannot develop a sense of self, which Terrace obviously does not argue for. As he himself explained a few decades ago (Terrace, 1985), children with congenital blindness develop language without exchanging mutual gazes with their parents. One could therefore think that in the absence of sight, self-awareness could develop through the other senses, and therefore also hearing and language. If this is the case, there is no longer any reason to think that the mutual exchange of gazes between mother and child phylogenetically preceded the other forms of emotional exchange to favor the development of the sense of self. I.e., recently Anna Ciaunica emphasized the concept of homeostatic co-regulation between mother and child during pregnancy (Ciaunica et al. 2021). At the root of this idea lies the consideration that the mother’s interoceptive and exteroceptive sensations are simultaneously co-experienced (albeit in partially different forms) by the infant in utero. The mother’s stress, for example, easily turns into stress for the child (and vice versa); or again, if the mother falls, both bodies experience the sensation of falling. In this perspective the two bodies are co-regulated. According to Ciaunica these considerations imply that the vison according to which the baby come into existence in an individualistic and solipsistic fashion should be questioned. Our first bodily experiences are lived through our mother’s bodily experiences, consequently they are in principle actually co-experiences. These co-experiences are also a first form of intersubjective exchange since through them mother and child mutually co-regulate their behavior (Ciaunica 2019). The first form of intersubjectivity is therefore shared among all mammals, since it is generated by the co-experience of the mother-child body dyad. Of course, at this point one could say that bodily co-experience and intersubjective exchange do not necessarily imply the development of self-awareness and the sense of selfhood and that, if anything, the reciprocal exchange of gazes would favor this latter acquisition. Indeed, the development of face-to-face interaction and the consequent habit of mutual gazes between mother and child can favor the development of a peculiar form

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Loving Gazes Even among Other Primates

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of intersubjective communication based precisely on emotional exchanges through the channel of sight. But this communicative characteristic is not exclusive to the human being. In § 4.4 we saw that macaques have a very dense intersubjective exchange with their mother in the first months of life and that this is nourished through a very dense network of crossed gazes. Moreover, these crossed looks favor the subsequent social development of the puppy (Dettmer et al., 2016). So we either accept the idea that macaques have a sense of self and other, transforming these concepts into something non-linguistic and much more basic than what is generally meant by these two terms, or we have to admit that, if it is true that mutual exchanges of glances favor the development of social cognition, it is equally true that they then need other phylogenetic acquisitions to transform themselves into a sense of self and of the other, i.e. language. In other words, macaques have this intense exchange of gazes with their mother but they don’t have language; that means it takes something macaques don’t have to develop language. In this regard it is truly crucial to observe the data collected by Matsuzawa (2006) on the evolutionary phases of the mother-child relationship: 65 million years ago mammals began to breastfeed their puppies, to date this behavior is present in 4500 species; 50 million years ago in primates the habit of the cub to cling to the parent began, the behavior is present in 200 species; 40 million years ago among the simians the puppies began to be embraced by the mother, the behavior is present in 80 species; five million years ago, 2 species of hominoids began to exchange mutual glances and smiles. Matsuzawa published these data in 2006, however, as we have seen in §4.4, subsequent data even allow us to further expand the group of primates that make use of reciprocal gazes between mother and cubs by including macaques in the list (i.e. Ferrari et al., 2009). Returning finally to Matsuzawa’s reconstruction, two million years ago the homo genus developed two other types of signals in the mother-child relationship: vocal exchanges and manual gestures, the latter favored by the permanently supine position of the human newborn, a characteristic which allowed him to have your hands always free for communication. The main change from chimpanzee to man in the mother/child relationship has been that the human mother, perhaps disadvantaged by the fact that the newborn was unable to hang on to her body as other primates do, less frequently holds the cub in her arms (therefore a perspective exactly opposite to Terrace’s in this respect). The human infant who is lying down has his hands free to try and learn to grasp objects, to make the first gestures which will then turn into forms of communication. If the chimpanzee mother holds, hugs and is in physical contact with the baby 24 h a day in the first 3 months of life, the human mother manages the relationship with less use of handto-hand contact and more extensive use of the voice communication. The newborn who needs help cries to be heard at a distance and in some cases the mother can even respond with only other vocalizations. A human infant can change position only after the first 2 months, which is not the case for example with macaques, which are able to roll over on themselves already at birth. In the previous paragraph we saw that human infants learn to recognize their mother’s face by associating it with the voice known in the womb. The chimpanzee, on the other hand, begins to visually

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recognize the mother’s face about 1 month after birth and uses her gaze as a salient reference stimulus (ibid.). According to the developmental ontogenetic reconstruction of chimpanzee intersubjectivity proposed by Tomonaga (2006), progressively from 0 to 12 weeks of age, the amount of time the pup spends gazing into the mother’s eyes increases. The amount of time the pup spends looking at its mother is inversely proportional to the amount of time she in turn spends cradling it. These reciprocal gazes between mother and son facilitate the development of primary intersubjectivity between the two, i.e. a dyadic social relationship maintained over time. This phase in humans is instead reached around 6 months, when children can observe objects for a long time or can have long gazes with the caregivers, but in which they cannot yet interact with a person who manipulates an object (triadic interaction). Between 4 and 8 weeks, chimpanzees learn to recognize each other’s gaze direction and to hold their mother’s gaze at each other for an increasing amount of time. Around 4 months, chimpanzees begin to decrease the amount of time they spend in their mother’s arms. At 3–5 months they begin to manipulate objects and at 8–9 months to do it in a combinatorial way (ivi). Until the first decade of the 2000s it was thought that chimpanzees stopped there, and that their learning occurred essentially by observing dyadic interactions (adult-object) and then by testing learning in another dyadic chimpanzee-object interaction (therein). As we have seen in §4.4.1, a few years ago it was thought that triadic interactions were not possible in non-human primates (ivi; Tomonaga et al., 2004; Tomasello et al., 2005). However, in recent years this idea has been clearly disproved by more rigorous empirical studies, chimpanzees actively interact in triadic contexts starting from the second half of the first year of life (MacLean & Hare, 2013; Bard, 2017). Therefore, if the arduous task of allowing the development of self-awareness and a sense of selfhood is entrusted to the intersubjective exchange of gazes, are we not equally obliged to recognize self-awareness and a sense of selfhood in non-human primates? Indeed, among non-human primates (and other animals) there are rudimentary forms of the sense of selfhood. For example, many chimpanzees recognize themselves in mirrors (Gallup et al., 2002; Kitchen et al., 1996); they show awareness of their own past actions (Martin-Ordas et al., 2013; Martin-Ordas et al., 2010) and seem to have a certain awareness of death, in that upon the death of a conspecific they implement some peculiar behaviors such as examining the body of the deceased or partially changing the own social behavior (Anderson et al., 2010). However, it must be emphasized that the sense of selfhood in chimpanzees is very different from that of humans. For example, even if it were true that chimpanzees recognize death when it strikes a conspecific, there is no reason to think that chimpanzees are aware that 1 day they themselves will die. Human self-awareness is more complex and involves aspects such as reflecting on one’s mental state, awareness of oneself as a unique entity, awareness of one’s emotions and thoughts, and awareness of being mortal. Is the difference between the sense of selfhood in chimpanzees and the sense of selfhood in humans quantitative or qualitative? Can this difference be traced

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Loving Gazes Even among Other Primates

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exclusively to the quantitative difference between us and chimpanzees in the use of gazes for communicative purposes?

6.3.1

The Sense of Selfhood in Chimpanzees and in Humans

In this section, I will briefly attempt to show that even the most radically embodied approaches to the study of the human mind cannot overlook the role of language in shaping the experience of consciousness. Naturally, in this paragraph we will not be able to cite all the philosophers who have dealt with consciousness and not even all the cognitive scientists who have done so. The purpose of the paragraph is not to provide an exhaustive review of the philosophical literature on the subject, but simply to show that a radically embodied approach to the study of cognition is not theoretically incompatible with a philosophical vision of man which foresees for language a fundamental role on the ontological level. Even the philosophers who have historically made more concessions to non-human animals in terms of consciousness have always specified that there is a profound difference between the self-awareness of animals and that of humans. In Creative Evolution (1907, ed. 2023) Henri Bergson argues that consciousness is an essential characteristic of life itself, which manifests itself in different forms and levels among living beings: consciousness is a continuous flow of perception and action and therefore is present in all forms of life. Life is an ever-expanding and adaptive driving force. In this perspective, not only animals, but even plants enjoy a certain primitive form of consciousness, it is not really a form of self-awareness, but rather a sort of intuitive awareness that guides them in their reactions to the environment. Similarly, in animals, consciousness manifests itself in the force of immediate instinct and action. However, Bergson specifies that there is a difference between the consciousness of human animals and that of non-human animals: the reflective component, which the latter naturally lack. In The Structure of Behavior (1942; ed. 2006) Merleau-Ponty outlines a difference in self-consciousness in animals and in humans which is actually quite similar to that of Bergson. He argues that the bodily experience of the world allows animals to become aware of their bodies and their motor and sensory capacities in the environmental context they live. However, the difference between this form of awareness and the human one is that it lacks the ability to reflect on one’s own experiences, or somehow to overcome them to create new ones: if a monkey picks a branch in order to reach a goal, it is because it is able to confer a functional value on an object of nature. But monkeys scarcely succeed at all in constructing instruments which would serve only for preparing others; we have seen that, having become a stick for the monkey, the tree branch is eliminated as such—which is the equivalent of saying that it is never possessed as an instrument in the full sense of the word. Animal activity reveals its limits in the two cases: it loses itself in the real transformations which it accomplishes and cannot reiterate them. For man, on the contrary, the tree branch which has become a stick will remain precisely a tree-branch-which-has-become-a-stick, the same thing in two different functions and visible for him under a plurality of aspects.

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This power of choosing and varying points of view permits man to create instruments, not under the pressure of a de facto situation, but for a virtual use and especially in order to fabricate others. The meaning of human work therefore is the recognition, beyond the present milieu, of a world of things visible for each “I” under a plurality of aspects, the taking possession of an indefinite time and space (Merleau-Ponty, 1963; ed. 1963, p. 175)

So animals would have their own interiority, but not a “pure conscience”, a “cogitatio”. The first phase of cognitive science saw an initial proliferation of theories of selfhood which in truth favored the meta-reflexive or in any case the linguistic and representational characteristics much more than direct bodily knowledge of the world: for Daniel Dennett, i.e., consciousness does not manifests to the subject in the first person as we would be inclined to imagine, but the illusion of the first person is created by the subject himself through the continuous self-narrative of the self and the philosopher who wants to study it will have to start from the linguistic accounts of this experience (Dennett & Weiner, 2017). Or again, Thomas Metzinger argues that the sense of self is a construction generated by neural processes: a complex of cognitive representations that generate the illusion of a unitary self, continuous over time and separate from the others (Metzinger, 2010). On the contrary, the embodied perspective in the field of cognitive science has given rise to a reawakening of interest in the body, often profoundly influenced by the ideas of Merleau-Ponty: Hubert Dreyfus for example, proposed the idea that understanding the world and interacting with it requires a form of bodily wisdom that somehow surpasses computational models and already in the 1970s the author predicted the decline of artificial intelligence’s dream of replicating human behavior based on the erroneous devaluation these theories made of the role of the body in determining the forms and contents of thought (Dreyfus, 1972). Evan Thompson develops a vision of the mind in which the self is the fruit not only of the brain, but in general of the entire body of the individual and even of the environment in which he lives; in his book Mind in Life (Thompson 2007) he explains in extremely clear terms what is often referred to as the hard problem of consciousness (Chalmers, 1996, 2021). Indeed, on the one hand, consciousness is commonly perceived as a phenomenon that takes place in first person; on the other hand, life is usually described in terms of objectivist, structural and functional properties: according to Thompson, this way of posing the problem is a dead end in philosophical terms since it leads either to reduce conscious experience to a study of structure and external functions and therefore to the disappearance of the possibility of seriously studying consciousness through the first person approach (more or less the materialistic vision) or to study consciousness trough the first person approach but neglecting the physical essence of external entities (more or less the idealist perspective). Thompson tries to solve this problem by reducing the gap between interiority and exteriority linked to that between consciousness and life: “the interiority of life is the interiority of selfhood and sense-making, which is a precursor to the interiority of consciusness” (op. cit. p. 225). According to him, the agreement between life and consciousness finds its embodiment in the Aristotelian

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Language Development without Mutual Gazes

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concept of psyche: that is, the ability of the organism to be active in various ways, the vitality of the body, the set of action goals of the body. Less radical than Thompson’s is the perspective of Shaun Gallagher and Dan Zahavi, who approach Merleau-Ponty when they assume as a presupposition of their philosophy the dichotomy between pre-reflective consciousness, i.e. an implicit sense of self perceived at an experiential level, and the reflective consciousness, i.e. the explicit, conceptual and objectifying awareness of the content of pre-reflective consciousness. The experiential datum is indispensable to the existence of reflexive self-awareness, which necessarily presupposes it (Gallagher and Zahavi 2021). Finally, it is worth mentioning yet another aspect of the embodied perspectives and we will do so through the speculations of Alva Noë who went so far as to extend the boundaries of self-awareness outside the physical body, even to external objects and social relations (Noë, 2010). As it is easy to understand, the philosophers of the first generation of cognitive sciences – given the leading role they give to symbolic and representative functions – will be less inclined to discuss the sense of selfhood in animals; however, it is appropriate to specify here that even the philosophers who adopt an embodied perspective, who therefore place more emphasis on the bodily experience than on the representational one, will probably always be inclined to admit that the symbolic and representational competences granted by language make human consciousness qualitatively different compared to the animal one. Even the apparently most radical approach, that of Evan Thompson, is forced to refer to the Aristotelian notion of psyche and the latter, as is known, is in any case organized into the three classical categories–vegetative, sensitive and rational–in which the last level is proper to man only.

6.4

Language Development without Mutual Gazes

If the joint attention obtained through gaze reading skills were an indispensable skill for developing language, subjects who for some reason cannot access this cognitive possibility should not be able to develop language. But this is not the case: both people with congenital blindness (who therefore do not read the gaze of others), and people on the autistic spectrum (in which joint attention is often deficient) can develop a language. It is interesting, for the purposes of our discussion, to see how this can happen. Congenital blindness causes very particular challenges for the affected child during the language acquisition phase. Beyond the issue of joint attention, which we will address shortly, there is first of all something much more basic that hinders learning the first words in these cases: sight is the sense of simultaneity, it helps us to reconstruct the coherence of a scene much faster than hearing, which responds to sequential inputs. As an alternative to hearing, blind children naturally use tactile exploration of objects, but this - unlike sight - requires a voluntary effort to seek sensory stimulation. Children affected by congenital blindness can therefore

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reconstruct a scene, even with a certain complexity and richness of detail; however, obtaining perceptual coherence for them has an extra cost in terms of time and attention to the task. Another difficulty that blindness causes to the child who is learning to speak is related to his impossibility to observe the articulation of linguistic sounds in the mouth of adults. This generates them a slight delay, compared to sighted children, in the acquisition of those phones whose articulation is visually very different. Furthermore, if phonetic substitution is influenced by both visual (b, m) and acoustic (m, n) similarity in sighted children, it is more influenced by acoustic similarity in blind children (Mills, 1983). To these perceptive peculiarities, we must then add the peculiarities of environmental compensations: caregivers are necessarily induced to use language, touch and vocalizations more to communicate with the child. Even the linguistic instructions seem to differ, perhaps precisely in an attempt to create those joint attention hotspots more easily obtained in sighted children through gazes. In fact, the language of children affected by congenital blindness shows some anomalies, which however do not persist over time and do not hinder the development of language in the adult, in fact at 36 months the language of a child affected by congenital blindness appears to be indistinguishable from that of a sighted child (Landau & Gleitman, 1985). The onset of vocabulary acquisition is usually somewhat delayed, but the sequentiality of language developmental stages is rather prototypical (Dunlea, 1991). It has often been argued that in blind children, symbolic play occurs enormously later than in sighted children (Rogers & Puchalski, 1984). However, if we take into account that symbolic play, which in sighted children manifests itself at about 18 months of age through specific interactions with objects, in blind children symbolic play instead takes the form of the use of different voices which converse with each other them to mimic various characters (Urwin, 1978; Fraiberg, 1977), it is possible to reassemble the phenomenon as early as 18 months (Urwin, 1978). From the ages of 5 to 9, these children also acquire symbolic play using objects (Bishop et al., 2005). The words learned initially are more or less similar to those of sighted children: words referring to objects prevail (35–51% of the words spoken), followed by words denoting actions (17–24%). The differences with sighted children can be found in an almost total initial absence of deictic expressions (which are initially 6% of the words spoken by sighted children) and instead by a much greater use of words concerning daily routines (10–14% of blind children versus 5% of sighted children) (Dunlea, 1991). In fact, the initial difficulties in using deixis are quite predictable: blind children learn to use this and that correctly when the relationship to be expressed is between themselves and the reference object, but they have much more difficulty when the relationship must starting from objects other than themselves (Mulford, 1983). In fact, the problems with deixis in these children are more than anything else due to a more general problem in acquiring a physical perspective external to the self: in the Dunlea study that we have just mentioned, in fact, the words that expressed actions were pronounced by children almost exclusively to

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Language Development without Mutual Gazes

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refer to themselves: for example they said “dance” while they danced; while in the control group the action verbs were used to express their own movements, those of other people, those of animals, those of objects. An analogous discourse can be made for words that express relationships, for example “still”, “more” or “no”; when a sighted boy involved in the study, for example, already used the word “no” to say “no poo” to express his surprise at seeing that the potty was still empty despite him having been sitting in it for some time, a blind girl used the same word only to express, for example, the refusal of food offered by the mother (Dunlea, 1991). Overgeneralizations also tend to be very small initially in blind children, particularly with the first hundred words acquired (Rescorla, 1980; Dunlea, 1991). According to Dunlea (1991) this would happen because the contextual information that the blind child receives is much less than that received by the blind child: overgeneralizations often occur on a sensory basis, and just as often the blind child cannot have sensory experience of many things present instead in the context of the sighted child. Another peculiarity found in the language development of blind children was found in 1985, when Landau and Gleitman found in English speakers a delay in the acquisition of auxiliary verbs. The explanation they gave of this is very interesting: on average, blind children heard them much less than sighted children because their parents tended to use much more declarative sentences and to respond much less with dry answers like yes/no (which in English require the ‘use of the auxiliary, i.e. “yes, it is”). Furthermore, the use of the auxiliary in such a short sentence probably tends to facilitate its acquisition in children. All these characteristics of the stage of language development in blind children are very interesting to illustrate how development also manages to lead to analogous results in different ways; but particular relevance for our discourse assumes the question of the orientation of the blind child’s attention. Dunlea (1991) studied the acquisition and use tendency of illocutionary acts in blind children. You have found that the pattern of acquisition of the illocutionary act is absolutely similar between blind children and sighted children; however, once this language proficiency is acquired, blind children make enormously greater use of it than sighted children. According to Dunlea “the blind child makes greater use of strategies to attract attention since the gaze cannot be exploited for this purpose. Likewise, they produce a greater number of requests for objects since they do not have access to the non-proximate environment” (ibid., p. 154, my transl.). In other words, the impossibility of attracting the parents’ attention through the gaze, according to Dunlea, is compensated for by a greater use of illocutionary acts, which would be used above all as a means of keeping in touch with the environment. In fact, a longitudinal study conducted in 2003 by Ann Bigelow on blind children confirmed their difficulty in learning about the existence of the untouchable world and the permanence of objects. He confirmed the existence of a slight delay in the acquisition of the first words. He also showed a slight delay, but not an absence, in the development of shared attention. This developmental pattern certainly suggests on the one hand that vision has an active role in the development of shared attention, but on the other it clearly shows that it is not necessary to it: in fact, blind children

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manage to maintain the attentional focus on an object with an adult using as if through their own body, i.e. by manipulating the object together with the adult. What’s more, the same study found that as the child learns his first words, it becomes increasingly easier for him to get involved in triadic relationships: therefore language enhances their shared attention.

6.5

Language Development with Sporadic Joint Attention

Autism is a neurodevelopment disorder that is diagnosed following the coexistence of two types of symptoms: anomalies in the communicative-social sphere and motor and/or cognitive stereotypies (American Psychiatric Association, and D. S.,, and American Psychiatric Association, 2013). Between these two conditions for the diagnosis there are individuals with very different characteristics: i.e. from boy who does not speak, suffers from very serious epileptic seizures and spends his days squeezing and then releasing a ball of foam rubber in his days in an obsessive movement without stopping and always equal, seemingly closed to the rest of the world; to Greta Thunberg (who was diagnosed with Asperger’s Syndrome), the young activist for sustainable development who already at the age of 15 managed to attract the attention of the media in many countries. The first boy will never be autonomous, he will never speak and his relationship with the outside world will never be fully known; in the second case, instead we have a person who is already accomplished at just 15 years old, who uses her brilliant intelligence and her oratory skills to try to change the outside world of which she therefore already has a clear idea. Between these two ends of the spectrum there is of course the infinite range of colors and shades that you can imagine in between. What unites all these people are “only” the two conditions of the DSM V diagnostic dyad. Historically, any attempt to create linguistic subgroups in the spectrum has failed (Pennisi, 2016). Even attempts to create diagnostic subgroups were abandoned, so much so that in the transition from DSM IV to DSM V all existing diagnostic sub-categories were eliminated because in clinical practice it became difficult to “pigeonhole” a child and often these shifts persisted until adolescence (Reichenberg, 2014). What determines this extreme difference is not known exactly; certainly, the severity of the diagnosis and an environment unable to provide the appropriate treatments are usually associated with worse outcomes; but often the best patient management systems are not enough to help him develop an independent life. Some children with autism never develop speech. Estimates of nonverbal autism range from 25% (Lord et al., 2004; Anderson et al., 2007; Norrelgen et al., 2015) to 50% (Kjelgaard & Tager-Flusberg, 2001; Magiati et al., 2011). In some cases, more complex approaches have been attempted, for example Norrelgen et al. (2015) estimate that in their sample (165 children with autism) 15% were completely non-verbal and 10% were minimally verbal (i.e. they spoke a few words).

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The autistic population is particularly interesting for the purposes of our discussion because from 2 months of age, children who will receive the diagnosis of autism at 36 months of age show anomalies in eye behavior, in particular they pay less attention to the eyes of adults than typically developing children (Jones & Klin, 2013). These anomalies persist in various forms throughout ontogenetic development and even into adulthood. That the anomalies begin around 2 months is probably not a curious coincidence, as we have seen in the first chapter, in the very first months of life the gaze becomes a catalyst for attention and seems to enhance the cognitive processes in progress. Children with autism have been one of the workhorses of Tomasello’s perspective, as they have enormous difficulties in participating in triadic interactions in conditions of joint attention (Mundy & Sigman, 2006; Congiu et al., 2016) and it seems that this difficulty is directly proportional to their communicative-linguistic skills (Tomasello, 2009 cites Mundy & Burnette, 2005). In general, the complex of social cognition disorders presented by children with autism (deficit in joint attention, difficulty in imitative learning, scarce presence or total absence of symbolic play, etc.. . .) are for Tomasello confirmation of the existence of a component of the human mind specifically dedicated to socialization and learning of culture, skills that start from the fundamental assumption that the other is an intentional agent, endowed with a mind of its own, an assumption that could perhaps be completely lacking in cases of more severe autism (Tomasello, 2005). In this case, therefore, language learning would not only be a link between the occurrence of looking at an object, the object and the child’s ability to follow it, but would also presuppose the child’s ability to understand that the adult is trying to communicate with him: or the ability to infer the communicative intent. The point however is that in fact this link between joint attention and word learning is not very clear: Gillespie-Lynch et al. (2013) for example, found experimentally that the acquisition of words in subjects with autism is more linked to the subject’s level of development rather than to his ability to follow the gaze of others. In fact, the study that Tomasello (2009) calls to support his theory (Mundy & Burnette, 2005) is a chapter that several other studies on the subject review. But the studies showing a link between deficits in language acquisition and deficits in shared attention in subjects with autism are all correlational (Bono et al., 2004; Dawson et al., 2004), i.e. they find a correlation between deficits in attention and language deficits, but they do not establish whether the relationship of cause and effect between the two phenomena is direct, nor the direction of this causality. When Gillespie-Lynch et al. (2013) questioned the nature of this correlation relationship, they actually found the presence of a third element that leads us to imagine an indirect type of causality: namely, the level of development of the subject. This data becomes more understandable if we refer it to the multimodal theory of language evolution developed by the same research group (Gillespie-Lynch et al., 2014) according to which the basis of social cognition that has supported the phylogenetic evolution of language is multimodal and includes all those social signals that express communicative intentions such as vocalizations, gestures, looks, etc.. . . . all traits that would be common in primates, but the norm in human children.

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Even other studies, which paradoxically support the idea that language learning presupposes the ability to infer communicative intent, however deny the linearity of the relationship between adult gaze following and word learning. Gliga et al. (2012), for example, found that three-year-olds’ ability to follow an adult’s gaze was not related to adult-observed word learning, and that - on the contrary - the child’s tendency to visually explore all objects that contended for the adult’s vocal label was a predictor of word learning success. After all, if the pursuit of the gaze were so important and irreplaceable, the learning of language would come closer to the Skinnerian vision: when the three inputs gaze/object/uttering of the word occur, then we have the learning output. Actually, it is much more plausible that language learning is the effect of the active exercise of all the intelligence of the subject as a whole: all the cognitive resources available to the single individual (whatever his deficits and his characteristics in general) are used to study the situation. Naturally, the perception of a communicative intent acts as a sort of stage light that pushes the subject to concentrate his energies on a precise part of the complex of stimuli he is receiving. Toy stores today are full of electronic gadgets that associate the image of a foot with an (unpleasant actually) electronic voice that says “foot”. Anyone who has made the mistake of buying one of these toys, perhaps hoping to teach his child a few words in his native language or in a foreign language must have sadly realized that he wasted his money. There is no communicative intent and therefore the child is not interested in articulated sound. He may perhaps press the button obsessively even for 20 minutes, but he will not learn the word which, precisely and among other things, is not in its natural context of use. In the context of natural use of a word there is both the communicative intent of the person pronouncing it and all the other contextual information that gives it full meaning. Undoubtedly sociality is a fundamental component in understanding the meaning of words, but we cannot ignore that sociality is not exclusive prerogative of man. All that complex of signals (vocalizations, gestures, proxemics, kinesthetics, prosody, looks, etc...) that we usually consider part of social cognition in addition to language certainly contributes to the acquisition of the first words. The existence of all these signals is linked precisely to the importance of the system they serve: sociability. If a child with autism does not speak, it is not (only) because he does not follow the gaze of others, it is because his social perceptions are generally deficient or anomalous and not synchronized with others (Pennisi, 2016): just to give an example, in the first months of life typically developing children prefer speech sounds to non-speech sounds, in children with autism this preference does not exist (Klin, 1991). But this extreme importance of social cognition is not unique to humans but to all social species. This richness is shared with other primates as we have abundantly seen in the previous paragraphs. And in fact it is not the link between the need to grasp the communicative intent and the learning of the language that we intend to contest here; what we believe it is essential to reflect on, however, is that many animals are able to learn the meaning of some words. Readers who own dogs don’t need special scientific proof to accept this reality; for all the other readers, on the other hand, it will be enough to think of the famous Kanzi, the male bonobo raised by

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The Need for Communication and the Intentional Communication

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the American researcher Sue Savage-Rumbaugh, who is able to understand over 500 English words and even actively use them to communicate through a system of visual symbols (Segerdahl et al., 2006).

6.6

The Need for Communication and the Intentional Communication

As we said (§3.2), Tomasello believes that joint attention could have developed in human beings by virtue of a vocation for cooperation that is particularly marked in humans. Specifically, in the first year of life children show that they are spontaneously cooperative with adults, after the first year of life culture begins to influence and direct (usually by enhancing it) this propensity. This propensity would manifest itself through three types of altruistic behaviors: helping adults who are doing something; provide information that others are looking for; share some material goods (Tomasello, 2009). We will not delve into the first question since, on Tomasello’s own admission, even some non-human primates lend help to their own conspecifics in difficulty in some situations. Instead, we will focus on the other two forms of cooperation, to see if they are actually uniquely human. The question of information sharing is really interesting: with a series of experiments conducted to show that children tended to point to adults objects that the latter were looking for, Tomasello and his collaborators came to the conclusion that children not only gave information, but also they couldn’t avoid to be informative. Conversely, primates tended to give the information sought by the actor only when they had something material to gain from it. The point is that the human newborn, as has already been said on several occasions, is the most in need of help of all the other newborns in the animal kingdom: the only real power it has is to inform the mother that she needs something or that something in the environment has disturbed it. If the newborn has heard a roar that has disturbed him, not having the power to escape, he will limit himself to informing his mother by crying. At 1 year of life (the age at which the children in the experiments conducted by Tomasello’s team were tested) children on average are still learning to walk, they roughly manipulate objects... however, on average the power to inform adults about what they need or what they have sensed in the environment is still the most important in their repertoire. For this reason, the intrinsic vocation for communication is certainly, as Tomasello argues, particularly developed in the human species, but not due to any special propensity for altruism, but because statistically it is better for a one-year-old child to always be informative with adults relatively to what it needs or what it has found in the environment as worthy of consideration. Perhaps these experiments should be interpreted more in light of the child’s need to communicate a recurring pattern of behavior rather than a desire to be helpful. After all, the need to be actively communicative could also derive from the loss of those forms of communication present in other animal species that do not require an active involvement of the issuer

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such as the emission of odors or the presence of ovulation. Chimpanzees, for example, are able to understand, by the smell of the urine of other conspecifics, whether or not they are part of their group and how close they are socially to them (Henkel & Setchell, 2018). The human being does not understand these signals, so it is possible that part of the communication had to move to the visual and auditory signals, which more often than the former require the voluntary act of the sender. As for the third point, i.e. the idea that children are more inclined than other primates to share goods, is very problematic. It is based on a series of experiments conducted on children and non-human primates which show that children are inclined to share their food with others and non-human primates are not. . . but as Tomasello himself admits, it is probable that simply children, usually well-nourished if not over-nourished, don’t really care about food. If Tomasello and his collaborators had conducted the same experiments asking these children to share their pacifier or toys to which they are particularly attached with other children, the results of the experiments would have been different. Furthermore, if children were naturally predisposed to share their goods as Tomasello claims, the siblings’ crises of jealousy for mothers nursing a newcomer would not find an explanation. Children are not willing to share what they consider particularly important to them and in this they are not all that different from other baby primates. Tomasello himself admits the indispensable role that the interest that the individual has for himself plays in maintaining the fitness of the entire species. The concept of cooperation between human beings should then be seen more than anything else as cooperation in the Griceian sense: communication in itself is an essentially cooperative act and in humans communication almost always requires an active effort on the part of the sender because other forms of communication where the sender had a more passive role, such as olfactory or gustatory communication via urine analysis by the receiver, is much less developed in humans than in other animals. The need for an active effort on the part of the broadcaster is not found only in the usual communicative interactions; but the child crowns his instinct to speak by trying and retrying vocalizations for a very long time not only in solitary monologues, but also making mistakes in front of adults with communicative intent, so adults by correcting him can help him learn.

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Merleau-Ponty, M. (1963). The structure of behavior. (A. L. Fisher, Trans.). Beacon Press. Metzinger, T. (2010). The ego tunnel: The science of the mind and the myth of the self. BasicBooks. Mills, A. (1983). Acquisition of speech sounds in the visually handicapped child. In A. Mills (Ed.), Language acquisition in the blind child. Croom-Helm. Mulford, R. (1983). Referential development in blind children. In A. Mills (Ed.), Language acquisition in the blind child (pp. 89–107). Croom Helm. Mundy, P., & Burnette, C. (2005). Joint attention and neurodevelopmental models of autism. In F. R. Volkmar, R. Paul, A. Klin, & D. Cohen (Eds.), Handbook of autism and pervasive developmental disorders (Diagnosis, development, neurobiology and behavior) (Vol. 1, 3rd ed., pp. 650–681). John Wiley. Mundy, P., & Sigman, M. (2006). Joint attention, social competence, and developmental psychopathology. In D. Cicchetti & D. Cohen (Eds.), Developmental psychopathology, theory and methods (Vol. i). John Wiley. Noë, A. (2010). Out of our heads: Why you are not your brain and other lessons from the biology of consciousness. Hill & Wang. Norrelgen, F., Fernell, E., Eriksson, M., Hedvall, Å., Persson, C., Sjölin, M., et al. (2015). Children with autism spectrum disorders who do not develop phrase speech in the preschool years. Autism, 19(8), 934–943. Pena, M., Maki, A., Kovaci, D., Dehaene-Lambertz, G., Koizumi, H., Bouquet, F., et al. (2003). Sounds and silence: An optical topography study of language recognition at birth. Proceedings of the National Academy of Sciences of the United States of America, 100(20), 11702–11705. Pennisi, P. (2016). Il linguaggio dell’autismo. Studi sulla comunicazione silenziosa e la pragmatica delle parole. Il Mulino. Reichenberg, L. W. (2014). DSM-5®. Essentials. John Wiley & Sons. Rescorla, L. (1980). Overextension in early language development. Journal of Child Language, 7, 321–335. Rogers, S. J., & Puchalski, C. B. (1984). Development of symbolic play in visually impaired young children. Topics in Early Childhood Special Education, 3(4), 57–63. Sai, F. Z. (2005). The role of the mother’s voice in developing mother’s face preference: Evidence for intermodal perception at birth. Infant and Child Development, 14(1), 29–50. Segerdahl, P., Fields, W., & Savage-Rumbaugh, S. (2006). Kanzi’s Primal Language. In The Cultural Initiation of Primates into Language. Palgrave Macmillan. Stern, D. N., Spieker, S., Barnett, R. K., & MacKain, K. (1983). The prosody of maternal speech: Infant age and context related changes. Journal of Child Language, 10(1), 1–15. Terrace, H. S. (1985). In the beginning was the “name.”. American Psychologist, 40(9), 1011. Tomasello, M. (2005). The cultural origins of human cognition. Harvard University Press. Tomasello, M. (2009). Why we cooperate. Massachusetts Institute of Technology. Tomasello, M., Carpenter, M., & Hobson, R. P. (2005). The emergence of social cognition in three young chimpanzees. Monographs of the Society for Research in Child Development, i–152. Tomonaga, M. (2006). Development of chimpanzee social cognition in the first 2 years of life. In T. Matsuzawa, M. Tomonaga, & M. Tanaka (Eds.), Cognitive development in chimpanzees (pp. 182–197). Springer. Tomonaga, M., Tanaka, M., Matsuzawa, T., Myowa-Yamakoshi, M., Kosugi, D., Mizuno, Y., et al. (2004). Development of social cognition in infant chimpanzees (pan troglodytes): Face recognition, smiling, gaze, and the lack of triadic interactions 1. Japanese Psychological Research, 46(3), 227–235. Urwin, C. (1978). The development of communication between blind infants and their parents. In A. Lock (Ed.), Action, gesture and symbol: The emergence of language (pp. 79–110). Academic. Wagner, G. P. (1996). Homologues, natural kinds and the evolution of modularity. American Zoologist, 36, 36–43. Zucconi, M., Ferini-Strambi, L., Palazzi, S., Curci, C., Cucchi, E., & Smirne, S. (1993). Craniofacial and cephalometric evaluation in habitual snorers with and without obstructive sleep apnea. Otolaryngology. Head and Neck Surgery, 109, 1007–1013.

Chapter 7

My Body Decides What I Can Do

7.1

Ostensive Act + Referential Act = Intention to Communicate

We have seen that the eyes have unique characteristics in the human species such as morphological characteristics and their ability to become more salient and reliable during emotional tearing. We have also seen that if eye contact is a rather widespread phenomenon in the animal kingdom, the pursuit of the gaze of others is more frequent as one approaches phylogenetically to the genus homo. Only chimpanzees and bonobos seem capable of interacting in triadic relationships and therefore of grasping a communicative intent in the gaze of the other and using it to infer the referent of communication, or rather of considering it an indexical tool in all respects. And in any case, it is not yet clear whether the behavior is present and to what extent in naturalistic contexts it is not influenced by humans. In humans, joint attention obtained through eye gazes normally facilitates the acquisition of language because it creates attentional hot spots in which the child’s cognitive processes are particularly predisposed to learning and receiving the message. However, we have seen that children with congenital blindness can replace eye gazes: the technique attested in the literature is the joint touch of an adult and a child on the same object. Even the way in which children with autism learn to speak has given us interesting information in this regard: in fact, if joint attention necessarily means that the understanding of the communicative intent must pass through eye contact and then the pursuit of the gaze of the otherwise, then the empirical data at our disposal disprove that shared attention and the acquisition of words can be correlated, at least in autism, because the acquisition of the first words is normally associated with the overall level of development of the child, therefore to the overall availability of channels for social communication or for the active exploration of the world.

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Pennisi, Gazes, Words, and Silences in Pragmatics, Perspectives in Pragmatics, Philosophy & Psychology 36, https://doi.org/10.1007/978-3-031-42571-4_7

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The idea proposed to resolve this empasse is that shared attention is not necessarily linked to following the gaze of the other and using it as an indexical. Shared attention can also be initiated through other channels. Six-month-old babies learn to follow an adult’s gaze considering it a referential signal after having received an ostensive act (a signal through which the communicative intention is expressed). In studies on shared attention, the ostensive act is almost always eye contact, which moreover - as we have seen - even at that age, has the power to amplify attention and cognitive processes in general. However, Senju and Csibra (2008) have experimentally shown a phenomenon that is perhaps also present in the experience of the reader himself: gaze following at that age is also activated by other ostensive acts, specifically by baby talk. So the sequence that leads to shared attention is an ostensive act + a referential act; or two subjects must both be concentrated on the same object of attention and the receiver must acknowledge a communicative desire to the sender. If the experiment of Senju and Csibra shows that right from the start the ostensive act can be not only visual, but also vocal; another experiment shows us that, once the sender’s communicative will has been established, the receiver will use all the tools at his disposal to guess the reference object. In fact, Nuku and Bekkering (2008), working with adults, showed that it is the presumption of intentionality that facilitates the consideration of the signal as a signal and not the presence of the visible iris on a white sclera. The two researchers have in fact shown that if the sender’s eyes are obstructed in such a way that the receiver believes that he is not really looking at something, the latter does not consider the signal referential. On the contrary, even if the receiver cannot look at the sender’s eyes because they are covered by sunglasses, but knows that he can see, then he will consider the referential signal and will use other clues, such as the orientation of the head, to grasp the reference object. In other words, the acquisition of the first words absolutely requires an ostensive act. This, however, is not only entrusted to the eyes in humans, but rather (perhaps more often) manifests itself largely through vocal signals (baby talk). The referential signal usually passes through the eyes, but even then, it can be replaced in other ways. While the ostensive act can equally (if not better) take place through vocal communication, the referential signal is conveyed more easily through visual communication rather than through other sensory channels (such as touch). But both the ostensive and the referential act can be, if necessary, conveyed with other sensory modalities. Just think of the case of Hellen Keller, the woman born deaf and mute who nonetheless learned to speak fluently (she held numerous conferences throughout her life) through mainly tactile training.

7.2

What Talking Parrots Have to Say on the Topic

Human beings are certainly not the only species in the world to have to undergo a long period of training in order to master their phonatory abilities. Birds also learn to use their vocalizations to transform them into what we usually call “bird songs”. The

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vocalization training stage has recently been compared to the babbling stage in humans, Lipkind et al. (2013) found striking similarities between the song learning stage in the mandarin finch (Taeniopygia guttata), Japan sparrow (Lonchura striata domestica) and in babbling babies. Bird songs have social functions, specifically through songs male birds transmit information about their aggressiveness, their physical qualities and the resources they have at their disposal; through the singing transmission of this information, they will attract or distance potential female partners and will induce the abandonment of any male competitors who will recognize the superiority of the singer compared to them (Collins, 2004). To the information transmitted with the songs are then added various vocal calls with various types of functions: most of the non-singing vocalizations identified in birds are alarm calls that differ not only according to the type of danger that is indicated. This type of signal is usually sexually dimorphic, as it is produced mostly by males of breeding age and during the breeding season. Interestingly, these types of signals are about as prone to flamboyant vocal ornaments as the bird emitting them. Other types of vocal signals widespread among birds serve to coordinate the group: some vocalizations identify who emits them individually, others instead are a sort of greeting, or rather they are emitted when two or more birds separate or reunite. Very often the vocalizations of birds have dialectal inflections, i.e. they are slightly different in some acoustic parameter from geographical area to geographical area (Marler, 2004). Irene Pepperberg’s famous studies have shown that parrots are potentially capable of understanding referential communication. The researcher trained her gray parrot, Alex, in the understanding and production of human speech and obtained that he became able to correctly use words related to more than 50 objects; 7 colors; 5 forms; correctly answer questions on the quantity of up to a maximum of 6 items; to distinguish three categories at a time (material, color and shape) and to use various other expressions such as “no”, “come here”, etc.. . . . Just like the children, Alex too was engaged in a continuous effort to learn vocal practice; both in solitude and in social contexts. Pepperberg’s idea is that “parrots, like children, have a repertoire of desires and purposes, which guide them in forming and testing ideas in dealing with the world; these ideas may be the first stage of the representation and categorization of cognitive processing” (Pepperberg, 2004:368). Therefore, also in the case of parrots, it is a question of a performative learning, which certainly requires a supportive social context, but also an active and very intense effort on the part of the parrot in trying to learn the use of vocal communication. The training with which parrots most easily acquire words involves a training model that Pepperberg has called the Model/Rival Technique. The bird is found with its handler and another human being. This human being is involved by the trainer in some interactions in which attention is named and focused on an object. The human names the object and behaves the way the trainer tries to make Alex behave. The parrot, in this context, sees the third intruder on the one hand as a model to follow, on the other as a rival with whom to compete for the attention of the trainer. The competition therefore pushes the parrot to imitate the most expert and through the experience then to reach learning (Pepperberg, 2004).

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Of course, Alex’s studies are not indicative of gray parrots’ cognitive abilities, since the Alex’s one is not a form of communication born spontaneously within the species; however, these studies reveal an important datum for our discourse: the complex communicative vocal abilities spontaneously present in many species of birds can even go as far as the articulation of complex sounds such as those of human linguistics ones in some species and with specific training. If Pepperberg, starting from this, wonders how parrots can learn to speak, the question posed here is in some ways the opposite: given that articulate language is associated with great advantages for the fitness of the species, why has it not spread in parrots as in human beings? What do human beings have that parrots don’t? At this point it is useful to discuss a fact on the understanding of intentionality in gray parrots (Psuttcus erithacus): with a complex experiment Péron et al. (2010) demonstrated that these animals tend to show more demanding behaviors when the experimenter shows not wanting to give them food, rather than not being able to give them food. This would suggest their ability to distinguish between different intentional states. However, other studies conducted on the ability to infer the visual attention of other subjects have given unclear results, which do not allow us to advance well-founded hypotheses in this regard (Péron et al., 2011). However, if parrots were able to interact in triadic contexts as infants learning to speak do, the best way to acquire words would have to be the joint attention of trainer and parrot on a third object, the presence of the model/rival it should be of secondary importance. Just the fact that the procedure for learning words is different between parrots and children suggests that the cognitive processing required in this case is different. In both cases we have a performative effort on the part of the learner and in both cases the imitation of the more expert speaker plays an important role. But why in the parrot does the procedure become more ergonomic if we externalize the part of the learner through the creation of the figure of the model/rival and in the child we manage to do without this role?

7.3

And the Hand Created the Intention

Let’s reflect on a question. Spontaneous vocalizations in birds, as we have seen, are learned both by self-correction of the learning birds and by learning from the social group. The meaning of these vocalizations concerns in some cases the type of danger from which it is necessary to flee (and therefore how to escape from it) or some characteristic of the subject who emits them (size, resources available for the partner, aggressiveness, etc. ...), or finally the relationship between the emitter and other subjects (greeting, removal, etc.. . .). The bird learns to convey information concerning itself and the relationship between itself and the others and only in the case of danger signals, the nature of objects external to the social group, but however of vital importance for it. Children who learn to speak, on the other hand, frequently talk with their parents about the objects present in the triadic relationship. Typically,

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And the Hand Created the Intention

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the parent shows the child an object and tells him its name. So, the child does not learn to speak in general, but learns to talk about something. A study conducted on eleven Italian children, for example, showed that among the first 10 words of children there are normally many dedicated to the identity of the caregivers (mom, dad, grandpa, granny, nanny, aunt, etc.. . .), but in the list there are always names of objects external to social relationships (doll, dindon,1 ball, pappa,2 babau,3 etc.. . .) (Majorano and D’Odorico 2011) which will surely have in some way been the object of shared attention with the caregivers. Terrace had argued (§3.1) that self-awareness in the human child arose thanks to the obligation to spend much face-to-face time with one’s mother. But as we have seen in § 5.3, Matsuzawa, on the contrary, pointed out that the impossibility of the human newborn to hang from its mother or to move like other newborns of non-human primates pushes it to a more frequently supine position and therefore to a greater use of vocalizations and hands rather than direct physical contact with the mother. Here we would like to suggest an alternative to the development of awareness of the self and of the other-than-self in the human child which in some ways subverts some assumptions of the socio-pragmatic theory in which the constitution of the subject seems to be linked first of all to the relationship with other intentional agents. Just the observation of vocal communication of birds, both spontaneous and artificially induced in Alex (and in other gray parrots by Pepperberg) highlights a characteristic of human communication: human beings always talk about something, very often this something is an unintentional object. While birds always use vocal signals in social contexts (excluding the learning phase, in which they can vocalize to perfect their signal); to express relationships of the subject emitting the signal with other individuals or to describe characteristics of the subject emitting the signal or to signal danger; on the contrary, human beings very often speak of unintentional agents and they do so even in playful contexts or in contexts that do not have a direct role in safeguarding the individual or group. Ball, pappa, baubau (to refer to a puppet dog), etc.. . . are among the most common first words in human beings. How come? Typically, triadic interactions in which shared attention acts as a sounding board for the child’s attention to an object, foresees that the adult shows the object to the child and that both play with the object, or manipulate it. The child turning and turning the object in his hands, experimenting with it, learns the characteristics of the latter. Let us borrow for a few lines the Husserlian concept of synthesis of the object percept (we are not focusing on the other intentional subject in this case, but precisely on the perception of objects) of which the philosopher speaks several times (cf. Husserliana XI; Husserliana XXXI; Logical investigations, VI; Cartesian meditations, II). Husserl borrowed the concept of epoché from Greek Skepticism.

1

Italian onomatopoeic word that mimics the sound of a bell. Italian word used by babies to refers to baby food. 3 Italian onomatopoeic word that mimics a dog barking. 2

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The epoché is disinterested contemplation, stripped of any prejudice or conditioning prior to the encounter with the object of knowledge. In Husserl the ego knows the world through this form of knowledge: the ego tests all the conditions of possibility of experience; it does not simply bring together representations, but it experiences the world by cumulatively acquiring all the experiences of it and therefore all the experiences related to the interaction between the ego and the objects of experience. The ego’s gaze moves to each object, giving it awareness of the latter: awareness is always awareness of something. The experience of many somethings gives rise to the problem of stream-of-consciousness synthesis. For the purposes of our discourse, it is good to focus on what emerges in relation to the identity of the objects: this is built through a synthetic procedure that unites all the different perceptions that the ego has had of that same object. If I observe an apple in front, then behind, then below, then above, then I observe its cross section, etc.. . . the set of perceptions that I have experienced in my various interactions with the apple are synthesized creating the ontology of the apple in the ego. This aspect of Husserlian philosophy interests us when it clearly illuminates the relationship between the synthesis of an object and the need to experiment with it in different ways. When children play with adults and the famous apple; by turning and turning the latter in their hands, children have the opportunity to experience the object not only visually, but also proprioceptively, olfactorily, gustatively, acoustically.When they have the apple in their hand, the apple is part of their body, but once they leave the apple on the ground it becomes other-than-me. Using the hands to manipulate objects means being able to experience through voluntary acts and being able to study the relationship between the self and the other-than-self through this experience. The hand allows a proactive experience of the object which speeds up and facilitates the cognitive synthesis. A clear perception of object boundaries also becomes a clearer perception of ego boundaries. And this at an even more basic level of the relationship to another intentional agent, the very level of the relationship between the self and world objects. That self-awareness that Terrace deems indispensable for language acquisition begins with the manipulation of the world; a manipulation in which the self actively and synchronously experiences taking and then leaving the object what self and other-than-self mean. When this form of learning partially shared with non-human primates is stably acquired, the child is ready to develop that extra degree of awareness that distinguishes himself from other conspecifics. But even this we share with non-human primates. It is only when manipulation and language come together in the inner language that that meta-reflexive complexity characteristic of man can definitively emerge.

7.4

The Only Talking Creatures in the Universe

In the light of these considerations, an attempt will be made to show that non-human primates do not speak because they do not have a supralaryngeal vocal tract; birds do not speak with the complexity of men because they have no hands to proactively

7.4

The Only Talking Creatures in the Universe

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experience the objects of the world through fine and complex manipulation. The fine and complex manipulation of objects makes them part of our intraspecific communication as part of our active and performative interest. The ability to manipulate many objects becomes the ability to create many words and words in turn become the building blocks of complex thinking. It could be argued that parrots (and many other birds) are no strangers to crude forms of object handling. Although they don’t really have an opposable thumb, they do have an opposable big toe which makes it possible for them to use objects. For example, it has long been known that parrots living in captivity are able to take a piece of food from the bottom of the cage, fly with the food clamped in the foot and then with the foot bring the food to the beak and eat it (Friedmann & Davis, 1938). However, the parrot that manipulates an object is in an unstable position because it has to stand on one leg only and the manipulation can take place almost exclusively with one paw only. In some cases the animal can rock on its back or stand on its shoulders and use both legs, but in this case the balance will be even more precarious. But hand comfort may not be the only other important factor to consider. Until now, we have only talked about peripheral morphological structures of language; but as it is known, there are some brain structures more involved in linguistic processes (Planum Temporale, Broca’s Area, the Arcuate Fasciculus, Cingulate Sulcus, the Insula, Superior Temporal Sulchus, Inferior Parietal lobe and finally the Central Sulcus) which appear to be key to the phylogenetic development of language. Recently it has been argued that probably the evolution of these structures has not been associated with language, but that these structures have been co-opted by language through exactative phenomena (Becker & Meguerditchian, 2022). The research group that advanced this hypothesis argued that in reality this peculiar cerebral architecture is associated with intentional or syntactic communicative behaviors and that these then, in humans, have been co-opted by language via exaptation. However, parrots do not seem to lack the individual intentionality described by Call et al. (2004), also as the ability to understand if an experimenter does not give them food because he does not want to or because he is physically prevented from doing so. We have seen this with the study by Péron et al. (2010): gray parrots show more demanding behaviors when a researcher shows that he is not willing to feed them, rather than that he cannot give them food. As for syntactic skills, as we have seen in relation to the studies on Alex and Kanzi, they can in part be acquired by some species, but are spontaneous only to the human chil. The point is that, as Pepperberg also argued in 1999, mental faculties can emerge as a result of particular environmental pressures if supported by body structures. The body structures that triggered the development of language were two: a supralaryngeal vocal tract capable of producing countless articulated sounds without excessive effort and the presence of two hands that it was possible to use and observe while manipulating the world (see Table 7.1). The body structure of the human being changed radically when with the transition to bipedalism (which allowed the expansion of the skullcap and the possibility of

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Table 7.1 The two bodily structures we need to develop language Ability to use hands comfortably for manipulation Parrot Non-human primates Human being

Voluntary control of the vocal tract for the production of complex sounds •

• •

•

carrying around a bigger and heavier brain); but the skull did not immediately reach the dimensions we know today, the first hominids started from the use of the hands to create tools. Use made possible by the ability to watch the hands at work and to do it from a comfortable perspective (not one of precarious balance). When, to this capacity, was added that of articulating complex sounds thanks to the lowering of the larynx and to all the changes described in §5.2, the two systems of thought (the manual and the linguistic ones) joined together creating that cognitive complexity which today appears so inexplicable. These two cognitive systems grow together: the human infant learns in parallel to speak and to manipulate the world in an increasingly complex way.

7.5

A Radical Embodied Perspective

In the first part of this book we have tried to show that communication through the eyes is certainly a very powerful tool in human cognition and that, compared to the rest of the animal world, it also enjoys some peculiarities such as the presence of emotional tears and the special propensity to prompt children to use adult eye signals, especially salient in our species, to facilitate language acquisition. Subsequently, we discussed some theories on language acquisition which see the eye as a fundamental communication tool in this delicate phase both at an ontogenetic and phylogenetic level. The impression one gets when examining these theories, however, is that they tend to tie in an excessive and misleading way the form through which shared attention usually manifests itself in the human species to the detriment of the evidence that, in the absence of the possibility of subject to sharing attention through gazes, these use other strategies, as the case of blind children clearly shows. Furthermore, the fact that in children with autism the development of language is linked much more to a level of general social development rather than to the simple ability to look the other in the eye or to engage in triadic interactions also tends to loosen the too tight grip between shared attention and word learning that has been hypothesized in the context of socio-pragmatic theory. This loosening of the grip is also confirmed by the possibility - also experimentally demonstrated by some

References

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research groups - of replacing the ostensive act of looking the child in the eyes with baby talk. The idea with which we tried to conclude the reasoning is that what makes human children special compared to the others is not so much the passive component of the pursuit of the gaze, although it undoubtedly facilitates the acquisition of words. What makes human children special is the union of two factors: the possibility of creating articulated sounds and the possibility of using the hands to manipulate the objects of the world. We share the first characteristic (at least in part) with birds; we share the second one with non-human primates (and other animals too to tell the truth; like koalas, chameleons, giant pandas, etc...), but we are the only animals in the world to have both characteristics. Certainly, having evolved in the branch of primates, in which social cognition is widely conveyed also through visual signals, makes this form of communication very important in humans. This makes it appear to us as an atavistic, instinctive and usually more spontaneous form of communication than the linguistic one. But our supralaryngeal vocal tract allows the expression not only of this social complexity, but also of the complexity of the interactions that through our primate hands we can have with the objects of the world.

References Becker, Y., & Meguerditchian, A. (2022). Structural brain asymmetries for language: A comparative approach across primates. Symmetry, 14(5), 876. Call, J., Hare, B., Carpenter, M., & Tomasello, M. (2004). ‘Unwilling’versus ‘unable’: Chimpanzees’ understanding of human intentional action. Developmental Science, 7(4), 488–498. Collins, S. (2004). Vocal fighting and flirting: The functions of birdsong. In P. Marler & H. Slabbekoorn (Eds.), Nature’s music: The science of birdsong (pp. 39–79). Elsivier Academic Press. Friedmann, H., & Davis, M. (1938). “Left-handedness” in parrots. The Auk, 55(3), 478–480. Lipkind, D., Marcus, G. F., Bemis, D. K., Sasahara, K., Jacoby, N., Takahasi, M., et al. (2013). Stepwise acquisition of vocal combinatorial capacity in songbirds and human infants. Nature, 498(7452), 104–108. Majorano, M., & D’Odorico, L. (2011). The transition into ambient language: a longitudinal study of babbling and first word production of Italian children. First Language, 31(1), 47-66. Marler, P. (2004). Bird calls: A cornucopia for communication. In P. Marler & H. Slabbekoorn (Eds.), Nature’s music (pp. 132–177). Elsivier Academic Press. Nuku, P., & Bekkering, H. (2008). Joint attention: Inferring what others perceive (and don’t perceive). Consciousness and Cognition, 17(1), 339–349. Pepperberg, I. M. (2004). Grey parrots: Learning and using speech. In P. Marler & H. Slabbekoorn (Eds.), Nature’s music (pp. 363–373). Elsivier Academic Press. Péron, F., Chardard, C., Nagle, L., & Bovet, D. (2011). Do African grey parrots (Psittacus erithacus) know what a human experimenter does and does not see? Behavioural Processes, 87(2), 237–240. Péron, F., Rat-Fischer, L., Nagle, L., & Bovet, D. (2010). ‘Unwilling’versus ‘unable’: Do grey parrots understand human intentional actions? Interaction Studies, 11(3), 428–441. Senju, A., & Csibra, G. (2008). Gaze following in human infants depends on communicative signals. Current Biology, 18(9), 668–671.

Chapter 8

Lateralization of Handedness and Language

8.1

What Is the Hemispheric Lateralization

Usually, in the scientific literature the term lateralization is used to refer to different phenomena, specifically to functional differences in the use of one side of the body rather than another (even with the same body conditions, i.e. even when we have configurations on both sides identical or nearly identical specular bodies); and is also used to refer to bodily asymmetries (usually cerebral but not only) between one side of the body and the other. Let’s take some examples. Let’s start with the functional meaning of lateralization. We are aware of some forms of this type of lateralization; for example, most humans write or perform precision tasks using their right hand. The widespread use of the right hand is a form of functional lateralization. There are also other forms of functional lateralization that we are not usually aware of: for example, the perception and expression of emotions involve the right hemisphere more than the left (Lindell, 2013a). Part of this evidence can also be shown with behavioral studies only (we do not necessarily need brain imaging), in fact some expressions, such as the smile, are more evident on the left side of the face rather than on the right (Indersmitten & Gur, 2003). The same right hemisphere bias also becomes evident with simple behavioral studies when evaluating the perception of emotions. For example, if a face is digitally composed by creating it with its left half on the left and the image of its left half mirrored and then on the right (Fig. 8.1), a more expressive figure is obtained than using the same paradigm but with right halves (Lindell, 2013b). One of the most macroscopic examples of body asymmetry, on the other hand, is the claw of the violinist crab (Fig. 8.2). As can be seen from the image, one claw is much larger than the other. However, the distinction between bodily asymmetries and functional asymmetries should be considered a general distinction, useful only to illustrate the concept in its complexity, but not for philosophical or scientific purposes. In fact, functional anomalies often correspond to anatomical anomalies and vice versa. For © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Pennisi, Gazes, Words, and Silences in Pragmatics, Perspectives in Pragmatics, Philosophy & Psychology 36, https://doi.org/10.1007/978-3-031-42571-4_8

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Fig. 8.1 The first image (a) is an expression of anger obtained through Midjourney. The two images below (b and c) are both manipulations of (a) made through Photoshop. The second image (b) is obtained by composing the left half of the model (a) and its specular counterpart together; the third image (c), on the contrary, is obtained by composing together the right half of (a) and its specular part. Normally people tend to consider (b) as more expressive than (c). Lindell, 2013a used the same technique but he started from real photo Fig. 8.2 Violinist crab. By NOAA http://www.csc. noaa.gov/acebasin/specgal/ inverts.htm, Public domain, https://commons.wikimedia. org/w/index.php?curid=1 974158

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example, the fact that emotions are more evident on the left side of the face is probably related to the fact that two-thirds of the lower part of the face in humans is innervated by the right hemisphere (Rinn, 1984), only as going up the innervations become more symmetrical (Matsumoto & Lee, 1993). Likewise, the largest claw of the violinist crab is naturally used by the animal in a different way and for different purposes than the right one. Therefore a function is said to be lateralized if it is not balanced symmetrically between the right or left axis of the body. Functional lateralization is usually accompanied by anatomical lateralization.

8.2

The Lateralization of Language

Historically, the study of lateralization began in 1865, when Paul Broca, explaining his findings from the last 5 years of research, declared to the Societé d’anthropologie in Paris “nous parlons avec l’emisphere gauche” (Broca 1865, p. 384). From 1865 until the second half of the 1970s, many studies were conducted on animals in order to discover anomalies in functional lateralization. For example, one of the most famous attempts was that of Otto Kalischer (1869–1942); in fact, he bought 60 parrots on which he looked for various forms of anatomical-functional correlation both bilaterally and for each hemisphere. However, he and all those who in those years undertook this type of study - although they found some small anatomical asymmetries - were never able to systematically correlate them to functional lateralization differences (Kalischer, 1905). Things changed when, in the second half of the seventies, Dewson, LeMay, Geshwind (just to name a few of the scholars who undertook these researches) realized that in the great apes (gorillas, chimpanzees, bonobos) (but not in the other primates that studied) the anatomical differences between the two hemispheres were consistent (Dewson III, 1977; LeMay, 1976; Geschwind & Galaburda, 1985). This awareness paved the way for an even closer comparison of the study of lateralization in the animal world. We will not retrace the historical stages of this journey; we will leap directly to today’s knowledge on the lateralization of auditory communication in animals.

8.2.1

Lateralization of Acoustic Signals Emerged before Primates

A recent cladistic analysis of the lateralization of vocal productions and receptions in non-human vertebrates (Ocklenburg et al., 2013) seems to indicate that in fact vocalizations perceived as belonging to conspecifics appear to be lateralized and almost always to the left. The data we are about to discuss is interesting because it

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helps us understand whether the left lateralization of language is a legacy of structures and symmetries inherited over millions of years, or whether it is a recent acquisition specifically linked to language. Let’s start with the fish data. Preliminary studies which do not yet provide very solid data seem to indicate the presence of forms of lateralization in the production of sound in some fish. In fact, some fish contract a part of the muscles of the swimming fin to produce sounds. Catfish appear to prefer the use of the right swim fin to produce sounds associated with social communication (Fine et al., 1996). In amphibians and reptiles we still don’t have clear data in this regard, instead the studies conducted on birds are interesting. The data on the lateralization of birdsong are not few, even if they are not yet sufficient to clearly determine how things are. Numerous forms of lateralization in song execution have been found in birds, but they are not all on the left. For example, among songbirds, zebra finches (Taeniopygia guttata) have been extensively studied. Well, various data seem to converge on the idea that in them the song production is not lateralized (Ocklenburg et al., 2013) and the same thing is true for various species of parrots, including the Amazonian ones with orange wings (Nottebohm et al., 1976; Heaton et al., 1995). However, a study conducted by Van Ruijssevelt et al. (2017) again on zebra finches showed, through a complex experimental paradigm centered on the spectral and temporal manipulation of bird songs, that an asymmetric sensitivity is present in this species in the processing of the spectral and temporal domain of the auditory forebrain which is similar to that of humans. In other species, however, things appear different: specifically in canaries (Nottebohm et al., 1976) and Bengal finches (Bengali finches, Lonchura striata var. domestica) there seems to be a prevalent use of the left side for the production of song (Okanoya & Watanabe, 1994; Okanoya et al., 2001). Going to the mammals, there are several interesting results. To begin with, dogs that hear vocalizations from conspecifics tend to turn to the right, while they tend to turn left if they hear other types of sounds behind them, such as thunderstorms. This indicates a probable left lateralization of the recall processing function by the conspecifics (Siniscalchi et al., 2008). Similar results were obtained with sea lions (Böye et al., 2005). Other interesting data also come from rodents. First of all, let’s say that rodents have a very marked tendency to auditory communication between conspecifics. An older study published in Nature in 1987 showed that in common mice (Mus musculus domesticus), experienced mothers of pups who had the ability to hear in both ears or only in the left ear, showed a marked preference for pup calls rather than for digitally produced sounds; but if these same mothers had their right ears plugged, the mothers seemed to no longer be able to distinguish between these two types of sounds. It therefore indicates that common mice tend to elaborate the vocalizations of conspecifics with the left hemisphere (Ehret, 1987). In particular, in this species it has been demonstrated through Fos brain volume imaging that the dorso-posterior area is activated exclusively in the left hemisphere during the recognition of conspecific vocalizations (Geissler & Ehret, 2004) and that the left auditory cortex seems to be activated predominantly in response to calls from conspecifics, while

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the right seems to respond mainly to the general spatio-temporal integration of auditory stimuli (Levy et al., 2019). Also in other rodents we have data consistent with this idea, the Mongolian gerbil for example has an advantage of the left hemisphere in various areas of the vocal, specifically: production of vocalizations; vocalization recognition; the amount of neurons and the volume in one of the sexually dimorphic neural areas located in the left hemisphere correlates statistically significantly with the rate of courtship vocalizations (Holman, 1998; Holman & Hutchison, 1991, 1993; Holman & Janus, 1998; Holman & Rice, 1996). We also have data in favor of the thesis that in Norwegian rats pain vocalization is predominantly lateralized to the left (Bianki & Snarskiĭ, 1988).

8.2.2

Lateralization of Acoustic Communication in Non-human Primates

Several data now show that intraspecific acoustic communication in primates appears predominantly left lateralized. Overall, we have evidence for predominantly left lateralization of communication with conspecifics in great apes of two types: behavioral and neuroscientific. Behavioral data seem to clearly indicate that in nonhuman primates there is a clear advantage of the left hemisphere in processing species-specific auditory stimuli (Hopkins & Fernandez-Carriba, 2002; Taglialatela, 2007). To give just a few examples, rhesus macaques have a predominantly right-sided head orientation following conspecific calls (Hauser & Andersson, 1994; Hauser et al., 1998; Ghazanfar et al., 2001). In Japanese macaques, discrimination of communicative vocalizations is higher with the right ear than with the left (Petersen et al., 1978). In Japanese macaques, impaired ability to discriminate communicative sounds following lesions to the left auditory cortex; ability intact instead with lesions of the right auditory cortex (Petersen et al., 1984). Among the behavioral data in non-human primates, however, a strong anomaly is found: vervet monkeys (Cercopithecus aethiops) show, like other primates, an asymmetry pattern in response to the vocalizations of conspecifics, however it manifests itself with an advantage of the right hemisphere (left ear) (Gil-da-Costa & Hauser, 2006). The data on vocality production also seems quite in line with what has been observed in humans. For example, when humans produce speech sounds, they tend to open the right side of the mouth before the left (Graves et al., 1982, 1985; Wolf & Goodale, 1987). Well, in line with this, marmosets show a greater opening of the right hemi-mouth for intraspecific communication (Hook-Costigan & Rogers, 1998). In chimpanzees there appears to be a tendency to open the left hemi-mouth more during involuntary vocalizations (hoots and screams) (Fernandez-Carriba et al., 2002) and a tendency to open the right hemi-mouth more during voluntary vocalizations (Reynolds et al., 2005).

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From a neuroscientific point of view, the most interesting data come from studies conducted on brain areas similar to the human Wernicke’s area and Broca’s area. In the human brain, in fact, there is a portion of Wernicke’s area called the planum temporalis that is larger in the left hemisphere than in the right. In 1998, Hopkins and co-workers discovered that the planum temporalis was larger in the left than in the right hemisphere not only in humans but also in the great ape group, at least for most specimens. This study received several subsequent confirmations. In that same year the data was confirmed in Science on a sample of 18 chimpanzees: 17 specimens (94%) actually showed the superior planum temporalis on the left rather than on the right (Gannon et al., 1998). And again a 2001 study confirmed it by subjecting 9 chimpanzees, 4 orangutans, 2 gorillas and 4 gibbons to magnetic resonance imaging (Pilcher et al., 2001). A PET study of Japanese macaques found that the left temporal pole became more active when listening to communicative vocalizations rather than non-communicative stimuli (Poremba et al., 2004). In 2018 a study conducted on 96 olive baboons (Papio anubis) found and confirmed this asymmetry, defining it “almost identical” to that found in humans (Marie et al., 2018). More recently, a Near-Infrared Spectroscopy study conducted on baboons baboons (Papio Anubis) found asymmetric hemispheric activations in animals similar to those in humans (right ear bias) (Debracque et al., 2020). Interestingly, these asymmetries in the planum temporalis present in great apes have not been detected in other primates (Pilcher et al., 2001; Hopkins et al., 1998). Therefore, we tend to trace the inheritance of this asymmetry around 30–40 million years ago, to the evolution of the Catarrhini, a common ancestor between men and great apes (Marie et al., 2018). In addition to the planum temporal, the areas corresponding to the human Broca’s area have also aroused the interest of neuroscientists: in fact, it appears larger on the left than on the right in chimpanzees, bonobos and gorillas (Cantalupo & Hopkins, 2001). It is also interesting to note that according to a study conducted by Hopkins et al. (2017) asymmetry in Broca’s area is more pronounced in chimpanzees more adept at certain manual tasks and especially if right-handed. However, compared to the data on the planum temporalis, these on Broadman’s areas 44 and 45 (homologues of Broca’s human area) are more controversial as they are not always confirmed by the rest of the scientific literature (Keller et al., 2009; Schenker et al., 2010). Regardless of the specific configuration that this form of lateralization assumes, however, overall the evidence for great apes lateralizing intraspecific communication to the left is strong. Whether it is as a result of phylogenetic inheritance or as a result of convergence, the lateralization of intraspecific communication - being a very common trait in the animal world and especially in great apes - probably brings significant advantages.

8.2

The Lateralization of Language

8.2.3

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Lateralization of Vocal Communication in Humans

Human language is left lateralized in 93% of people (Knecht et al., 2000a, 2000b). This is the only fact to take seriously into consideration when we want to simplify the discourse on the lateralization of language in humans. However, it is worth specifying that the idea that the lateralization of human language is totally to the left has recently been challenged by the model proposed by Hickok and Poeppel (2007). Gregory Hickok is essentially known for two philosophical-scientific reasons: the first one was for having raised various objections, some of which are valid and still debated in the literature, on the interpretations that are frequently provided in relation to the functioning of mirror neurons (Hickok, 2014). The second one is the neurolinguistic model that Hickok built together with his PhD student Poeppel. Poeppel questioned the absolutist assumption that language function was entirely left lateralized. Initially this idea seemed like madness because the literature was actually quite consistent about it. Gradually, however, Hickok and Poeppel, using both neurolinguistics data and clinical data, managed to demonstrate that the phonemic (non-semantic) discrimination of phones within words is not left lateralized. That is, if I have to distinguish two different phones in two meaningless syllables such as «fa» and «va» I use the left hemisphere; but if I have to distinguish between ‘fan’ and ‘van’, both hemispheres contribute to the task. This showed that, although the production of language remains the prerogative of the left hemisphere; language comprehension, by contrast, at least partially involves the right hemisphere and that understanding phonemes within a word was a different process and only partially superimposed on distinguishing between different syllables in meaningless contexts. Starting from these assumptions, the two scholars formulated a two-way model of auditory processing of linguistic sounds that followed the one that had recently been elaborated by Milner and Goodale (1995) for sight. Both models were quite lucky; that of sight provided for a ventral route and a dorsal route. The ventral route would be linked to the ability to see objects as a whole, or to be able to perceive an object as a whole. Subjects with damage to this path are able to use objects correctly, but do not grasp them as a whole. For example, if I had a striped vase in front of me here and I had damage to this street, I would see the stripes of the vase as separate entities with respect to the vase. This type of disturbance is a form of visual agnosia. The dorsal pathway, on the other hand, would be responsible for how the patient interacts with objects. The patient who has damage to this pathway can see objects well and recognize them correctly but have difficulty interacting with them. The model of separation of the so-called ‘what stream’ and ‘how stream’ has been very successful in the literature not only because it explains many clinical phenomena, but also because it is actually consistent with the fact that recognizing an object and doing something with it - even if they start from same input - they are in fact two very different activities that overlap only to the extent that I know better how to interact with an object if I know what it is. But if an object is coming at me, I will try to grab it even before I have recognized it and likewise I can recognize an object without physically interacting with it. The path of the thing connects the vision of the

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Fig. 8.3 The dual-stream model of the functional anatomy of language

object to the concept we have of that object, amplifying our performance in using it. A pianist who sees a piano will be able to interact with it much better than who unfortunately have no musical competence. Influenced by these studies, Hickok and Poeppel proposed an organization of two networks, one dorsal and one ventral, also for the auditory processing of speech sounds (Hickok & Poeppel, 2007). Specifically, the two authors have shown with data coming from the clinic, from experiments conducted with TMS and experiments conducted with the Wada procedure, (a technique that allows one hemisphere to be completely anesthetized, leaving the other awake) that both pathways start by a bilateral activation of the posterior part of the superior temporal gyruses and superior temporal sulci (cf. Figure 8.3). At this point the sound is processed in parallel by two pathways, the ventral pathway which from the superior temporal gyri and superior temporal sulcus projects bilaterally to the posterior part of the inferior temporal cortex and to the anterior part of the inferior temporal cortex with marked left lateralization. This path is the one that transforms sound into meaning. The dorsal pathway, on the other hand, is completely lateralized to the left and from the superior temporal gyri it projects onto the Spt area, which is a region posterior to the Silvian fissure and two frontal regions of the left hemisphere. This path is the one that allows us to create for ourselves a representation of the type of articulatory movement that our interlocutor made to utter those words. (this image has been adapted from Fig. 8.1 of Hickok & Poeppel, 2007). To clarify, the dorsal route is the one that allows us to answer questions of this type: “in the sentence ‘Martha bought a ceramic vase’, how many times does the syllable ‘-va’ appear?” What does this mean in practice? That if I ask you to distinguish between “va” and “pa”, you use the dorsal network to answer, i.e. the one that creates representations of the motor pattern that our interlocutor used to articulate those sounds. Even if for the listener these sounds have no meaning (because perhaps they are in a language that he does not know), he is able to reproduce them. Meaning is not important for analyzing sound through this pathway. Although of course we constantly use semantic context to disambiguate phonemes; but if we were left with only the dorsal pathway, we could still create motor representations of the heard sound. This process is exclusively left lateralized. On the contrary, if I ask you to distinguish

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between “van” and “fan” the process will be essentially bilateral with slight lateralization to the left; the subject is acoustically extracting the known characteristics of these phoneme strings, comparing them with previous experiences of the same phoneme strings. In fact, the organization of language (which we remember in Greek was λóγoς, a word with which many Greek philosophers also referred to thought) in the motor and semantic distinction can only lead to the need for two separate circuits for vision: one to recognize the object (meaning), the another one to know how to use it. But the fact that the discrimination of syllables in semantic context would occur bilaterally in the posterior parts of the inferior temporal cortices and on the left in the anterior part of the inferior temporal cortex, all in all, does not undermine the general principle according to which most linguistic functions are lateralized to the left.

8.3

Lateralization of Handedness

We saw in the last paragraph that the lateralization of intraspecific communication seems to have been lateralized for a long time. In our great ape cousins then this lateralization seems to have settled on the left. Given that, we are trying to understand the relationship between cerebral asymmetry and the two dominances strongly pushed to the left in the human being, i.e. language and use of the hand, we will now try to understand when the lateralization of the dominance of a paw or a hand seems to have appeared in phylogenetic history. However, before this review it should be noted that - as demonstrated by Rogers, Vallortigara and Andrew (2013) through the comparison between the amphioxus and Hakouella to which we will now devote a few lines - the evolution of lateralization, although favored by hereditary phenomena, can also appear by convergence. Let us see how the authors arrived at this conclusion. For one to speak of lateralization, we must be in the presence of an animal that has a bilateral and tendentially symmetrical organization. The eumetazoa, or that sub-kingdom to which animals belong in which histological differentiation gives rise to real tissues (to which man naturally also belongs) are divided into radiates and bilateria. In the radiata it is possible to imagine a central axis of the body that passes through the mouth and around which the animal is able to respond in the same way to stimuli that strike the body from any direction. This radial symmetry is not only external to the body, but also internal. Jellyfish, corals and sea anemones are banned. In the bilaterians the fore and hind legs begin to exist in the animal; the body tends to have an elongated shape and it greatly enhances locomotion capabilities. The emergence of an anterior direction of the body soon led to a process of cephalization of the sensory organs. In bilaterians we can always distinguish the cephalic from the caudal end and the dorsal from the ventral side. But in order to speak of lateralization we will have to wait for the chordates. Chordates are animals halfway between vertebrates and invertebrates, they have a thin cord in the center of the body that acts as a vertebral column. We are talking about small animals that date back to the

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a

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Lateralization of Handedness and Language Myomeres

Mandibular Eye artery

Fin Bands above notochord

Spinal (nerve) cord Brain

Tail (caudal process)

Nostril ? Upper lip Tentacles over mouth opening Lower lip

Endostyle

Denticles

Branchial pouch and bar

Atrium Heart ?

Ventral aorta

b

Gonads Intestine Atriopore Bands on notochord (protovertebrae) Notochord

Rostrum

Tentacles over mouth opening

Anus

Myomeres Fin

Endostyle Branchial slits and bars

Atriopore

Gonads Atrium

Tail

Anus Intestine

Fig. 8.4 Comparison between Hakouella (A) and amphioxus (Mallatt & Chen, 2003)

Cambrian and even Precambrian periods, we are talking about 540 million years ago. However, the evidence we have today of this is very solid since it is based on the behavior of a still existing chordate, the Branchiostoma, better known as Amphioxus. The branchiostoma has a body structure quite similar to that of vertebrates: first of all it is a cephalochordate. The body structure is linear; on the back the myotomes, i.e. muscle segments, allow the body to swim with lateral movements. Of course, compared to the displacements allowed by a jellyfish, we have a remarkable locomotor power, however the amphioxus rotates continuously while swimming, so - although it can also move over long distances - it could never pursue a prey, for example. In fact, in order to eat, the adult amphioxuses attach themselves to the bottom of the sea, or on whale carcasses and through the gill slits they filter incoming water currents rich for them in nutritive particles. The oral tentacles are central and the gill filters are present in large numbers on both sides of the body. However, the amphioxus larva has a different structure. It has the mouth on the left of the body; glandular secretions secrete a sticky substance on the left side around the mouth. This sticky substance traps small prey items which are swallowed as soon as they become entangled in this substance. An important characteristic of the amphioxus is that it does not have two eyes. Another interesting small animal was recently described by Mallatt and Chen (2003), it is always a chordate, dating back to about 530 million years ago. The genus is called Haikouella, based on about 300 fossil records found in China (Fig. 8.4a), compared with the body structure of the cephalochordate (fig. 12 B). In Hakouella we first of all have the brain, therefore no longer just the central nervous system of the elongated shape of the amphioxus; we have lips that can open and close the tentacles of the mouth and above all we have eyes, two separate

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Fig. 8.5 Amphioxus. The n° 16 is a light sensor. The n° 3 is a neural tube. Creative commons: Piotr Jaworski, PioM

eyes placed one on each side of the body. The presence of the eyes suggests that Hakouella was capable of perceiving, indeed seeing, prey from a distance. The cephalochordate also had some vision, in Fig. 8.5 the nerves in yellow at number sixteen, were light sensors; they then converged centrally in the neural tube. This complex is usually considered a frontal proto-eye. The eyes of vertebrates are thought to come from here. From an organ that was initially single and then split in two. As we have just said, in the amphioxus the nerve plexus of the oral cavity is only on the left not only in the larva (in which the mouth is on the left) but also in the adult it remains only on the left. A consequence of this asymmetry is that the input coming from the frontal eye has a very fast prey grabbing movement response, while if the light change is detected to the right, the prey grabbing movement is slower. The presence of two distinct eyes from Hakouella onwards led to the formation of bilateral cerebral motor centers with analogous and well-balanced characteristics, yet examples of lateralization are present throughout the animal kingdom, even in phylogenetically distinct branches. This indicates that lateralization is not handed down only by phylogenetic inheritance, but also evolves in a species as a result of contact with the environment, i.e. due to the effect of the environment on the genes, therefore by convergence. So to sum up, in the larvae of the branchiostoma a somatic asymmetry was manifested (i.e. the mouth was moved to the left), this was followed by a lateralization of the central nervous system. Having established this, we analyze data on lateralizations of the limbs of non-primate animals.

8.3.1

Did Limb Lateralizations Exist before Primates?

A rather widespread idea in the scientific literature on lateralization is that manual dominance, at least that strong human dominance, is a specific trait of human beings, or in any case to a lesser extent of primates. Ströckens et al. (2013), for example, through a cladographic comparison of all non-extinct vertebrate species, came to the

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conclusion that - although the preference for a limb is a fairly common trait among vertebrates - only in humans is it so marked and thus independent of the task. Among the animals most frequently tested for limb preference we find, of course, domestic animals. According to several studies, dogs do not appear to have a marked preference, i.e. they are more or less likely to be right-handed, left-handed or ambidextrous (Barnard et al., 2017; Marshall-Pescini et al., 2013; Schneider et al., 2013). This data has been variously reproduced with different types of tests such as the Kong test or the first-stepping test. Nonetheless, the results remain controversial. Tomkins et al. (2010), for example, by comparing these two tests, found different data with respect to the rest of the literature: if their study confirmed the essentially random diffusion of the three possibilities (right-handed, left-handed, ambidextrous), first-stepping instead reported a much higher percentage of the presence of lateralization (strong right). The presence of conflicting and inconsistent data, linked to the fact that the evolution of dogs has been strongly conditioned by man’s needs, does not make these animals a good testing ground for our reflections. Much more interesting data for the purposes of our discussion come from studies on parrots. Parrots have inferior limbs that allow them some level of manipulation of objects. Two Australian researchers, Maria Magat and Culum Brown studied the relationship between foot and eye lateralization in eight different species of parrots. The preference of the right or left side was quite random, but there was a very strong correlation not only between lateralization in the use of the foot for manipulative purposes and eye, but also between the level of lateralization and manipulative skills. From these data, the researchers conclude that cerebral lateralization, in addition to being an almost ubiquitous trait in parrots, favors greater adaptive chances as it allows the animal to better manipulate food (Magat & Brown, 2009). A few years later, the two researchers extended the data on the relationship between manipulation and eye lateralization to 16 different species of parrots (322 individuals) and proposed a rather convincing interpretation of their data: the limb preference of parrots is linked to the dominance of the hemisphere that is analyzing the object in question. In other words, if the animal is analyzing the piece of food with the right eye, it will manipulate it with the right hand (Brown & Magat, 2011). Another case study that will provide us with useful food for thought concerns hand dominance in marsupials. Giljov et al. (2015) compared the dominance in the use of the limbs in seven species of marsupials, in this way they found an overwhelming regularity: the races that use two legs to move have a very strong left lateralization of the forelimbs, comparable to that of human beings; the breeds that move using the four legs instead have an extremely weak lateralization. The researchers conclude (and this conclusion was also endorsed by Vallortigara, see Vallortigara, 2015) that the presence of manual dominance is not linked to the phylogenetic relationship, but to the posture of the species. The data on non-human primates, although they still need further study, however show clearly that it is not necessary to have developed the language to have manual dominance. Versace and Vallortigara (2015) argue that manual dominance in humans probably has a multifactorial onset (Versace & Vallortigara, 2015) and in fact the data on non-primate vertebrates seem to be in line with this: in parrots

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manual dominance seems linked to the need pairing of the foot with the eye (hemisphere) which analyzes the object and has an adaptive value because it allows the parrot to operate more specific manipulations on the food; in marsupials, on the other hand, dominance appears to be linked to posture, a posture that frees the lower limbs from the task of moving (favored by the symmetry of movement), favors the development of lateralization for fine manipulation.

8.3.2

Relationship Between Hand Dominance and Lateralization of Vocal and Gestural Communication Behaviors in Primates

If the onset of handedness is multifactorial and not necessarily linked to phylogenetic kinship, observing what happens on this side among non-human primates can help us understand whether, and possibly how, manual dominance in humans is linked to linguistic lateralization. We saw in §7.2.2 that in great apes intraspecific vocal communication is predominantly lateralized to the left; if the hand also showed the same dominance, then it would be all in all implausible that manual dominance in humans was somehow related to language. Conversely, if nonhuman primates did not show marked hand dominance, this could indicate a role of language in the extremization of human hand dominance. In 2002, Hopkins and Carriba, analyzing the literature data on hand use preference in performing communicative gestures in primates, found that the most interesting phenomenon in preference bias was that gorillas, bonobos and chimpanzees actually predominantly use the right hand. However, the most recent data, thoroughly analyzed by Caspar et al. (2021), give us a rather enigmatic picture of the hand dominance problem: population-level hand dominances are quite rare in nonhuman primates and there does not seem to be a clear phylogenetic or ecological rationale behind a species’ tendency to preferentially use a hand rather than another. Furthermore, none of the species evaluated has such marked hand dominance as the human species. For example, in baboons (Papio anubis), gorillas (Gorilla gorilla), and chimpanzees, object manipulation also appears to be preferred with the right hand (Vauclair et al., 2005; Hopkins et al., 2011). But if the percentage of righthanded people in these species settles at around 50%, in humans the percentage is much higher (90%, see Lozano et al., 2017). To complicate the puzzle there is also another fact: the extremes of manual dominance does not seem to be the exclusive prerogative of Homo sapiens, but according to Lozano et al. (2017) was already present in the Neanderthal. As mentioned in § 7.2.2, chimpanzees, bonobos and gorillas show the brain area homologous to Broca’s area larger in the left hemisphere than in the right, exactly like humans (Cantalupo & Hopkins, 2001). Well, Taglialatela et al. (2006) found that chimpanzees that are habitually using their hands for gestural communication

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show a larger Broca’s area homologue than those that do not habitually communicate with their hands. Additionally, chimpanzees tend to prefer the right hand in gestural communication; this preference for the right hand for gestural communication becomes even more pronounced when animals accompany the gesture with a vocalization (Hopkins & Cantero, 2003). When chimpanzees produce communicative behaviors towards humans, they use both vocalizations and hand gestures, but the vocalizations to a much greater extent. However, these communicative behaviors are always accompanied by a left lateralized activation of the inferior frontal gyrus (considered the homologue of Broca’s area in humans) (Taglialatela et al., 2008). These data might suggest that theories on the gestural origin of articulated speech may have a scientific foundation in the behavior of our phylogenetic cousins; however a study by Taglialatela et al. (2011) conducted with PET clearly shows that the left lateralization found during these left behaviors is exclusively linked to vocalizations, as it is absent when the animals produce communicative hand gestures. Meguerditchian et al. (2012) confirmed on 40 chimpanzees the absence of left asymmetry in the inferior temporal gyrus during the production of a communicative gesture (clapping) frequently used by these animals to attract the attention of a distracted addressee; however, they found left lateralization of the planum temporalis. However, it should be noted that the act of clapping cannot be considered an exclusively manual sign, but perhaps rather mainly an acoustic one since it achieves its purpose if it is received acoustically, and not visually by the recipient. Meguerditchian et al. (2013) tried to remedy the confusion present in the literature on hand dominance in nonhuman primates and on the meaning it assumes in relation to communication by rearranging the already existing data in the scientific literature on the basis of a task-dependent distinction: specifically the researchers distinguished between tasks that required one hand dexterity and tasks that required two-handed coordination. In doing so, they found a satisfactory homogeneity in the results: in unimanual actions no particular dominance in primates emerged; conversely, in actions requiring the coordinated use of both hands, there is a preference of the right hand for the precision task in baboons, red macaque monkeys, chimpanzees, bonobos, gorillas, and human infants. Even communicative gestures show a clear predominance of the right in primates, at least this has been demonstrated for chimpanzees, bonobos, gorillas and baboons. However, there does not seem to be a correlation between manual dominance in coordinated bimanual actions and use of the communicative gesture (Meguerditchian & Vauclair, 2006; Meguerditchian et al., 2010, 2012; see also data on linguistic lateralization and manual dominance in §7.4). For this reason, Meguerditchian et al. (2013) proposed an explanatory model in which hand dominance in object manipulation through the coordinated use of the two hands and hand dominance for gestural communication, although partially overlapping, are essentially independent.

8.5

8.4

What Is the Lateralization of a Function for?

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Relationship Between Language Lateralization and Hand Dominance

Most humans have left lateralization of speech. However, 7% of the human population escapes this rule, which instead has language lateralized to the right (Knecht et al., 2000a, 2000b). Given the strong relationship that has always been found between the hand and speech, one would expect all left-handed people to be lateralized to the left, but in fact this is not the case. There are right-handed rightlateralized for speech, left-handed right-lateralized for speech, left-handed leftlateralized for speech, and the majority of the population are right-handed leftlateralized for speech. However, the combination of these pairs is not random, but linear and can be expressed with a mathematical formula. As an indication, we can say that among subjects with linguistic lateralization to the right, 4% are righthanded, 15% are ambidextrous and finally 27% are left-handed. This means that manual and linguistic dominance appear linked, but that it is not absolutely true that right-handed people for language are always left-handed, nor that left-handed people are always right-lateralized, indeed only 27% of left-handed people are lateralized to the right. The development of hand dominance is thought to be linked to both genetic and cultural (or individual) factors. First, sex seems to be somehow related to hand dominance, since for every 12 left-handed men there are 10 left-handed women. Some fetus behaviors have been linked to a possible indication of dominance. Specifically, the majority of human fetuses already 14 weeks after conception tend to prefer right thumb sucking and this preference is strongly correlated to school-age dexterity. Furthermore, most newborns prefer to sleep with their heads turned to the right and this preference has been correlated with the subsequent development of manual dexterity. Finally, still of interest to this topic is that hand dominance can be influenced by readiness to visualization as shown by a study conducted on children with congenital muscular torticollis. In fact, this pathology, since it leaves some muscles in the neck contracted, forces the child to be permanently turned to the opposite side. If the child has a left contracture, he will always be turned to the right. This will make it much easier for him to observe his right hand than his left (see Fig. 8.6). Well Ocklenburg and collaborators in 2010 showed that the watched hand has, compared to what happens in typically developing children, much more likely to become the dominant one in mature age.

8.5

What Is the Lateralization of a Function for?

But why is intraspecific vocal communication so strongly lateralized? In 2004 Rogers and collaborators advanced a very interesting hypothesis in this regard, starting from some data they produced on chick lateralizations. According to

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Congenital torticollis

Head tilted toward affected muscle

Chin point away from contracted muscle

Contracted SCM muscle

Fig. 8.6 Congenital muscular torticollis

them, the presence of lateralization phenomena would allow the individual to process and pay attention simultaneously to multiple stimuli at the same time. In practice, chicks have an advantage of the right visual hemifield in stimulus discrimination tasks and of the left visual hemifield in the detection of emotionally relevant stimuli, such as possible predators. Here according to Rogers, having two independent hemifields with information that do not conflict in the information detected would facilitate the execution of both tasks. Indeed, making efficient use of the brain probably underlies strong evolutionary pressure, given that the brain in humans is 2% of body weight but accounts for about 20% of our consumption (Raichle and Gusnard 2002). Furthermore, according to Vallortigara (2006), making a careful use of the cortical tissues avoiding useless replications would be an important saving principle given that the human skull has the problem, greater than the skulls of other animals, of having to be born from an extraordinarily small canal to its dimensions. In practice it is a sort of expertise that makes the function more effective, that is, it makes performance in that function better, making all cognitive functioning less burdensome during its functioning. The flip side, of course, is that if there is no redundancy in the brain, loss of function in the responsible hemisphere results in total loss of function. We lose the ability to produce speech almost completely and in almost all cases if we lose Broca’s area, regardless of anything else that may be happening in the right hemisphere. If we were to apply this thesis to language, we

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What Is the Lateralization of a Function for?

123

could therefore argue that language is left lateralized by phylogenetic inheritance. In turn, phylogenetic inheritance has taken advantage of lateralization because this hyper-specialization, in addition to optimizing linguistic performance, allows us to do other things while hearing and speaking. Indeed, object recognition and use of objects are activities that we typically perform while doing other things. And in fact the same team in which Milner and Goodale had worked, noticed - at a certain point - the presence of functional asymmetries in their doubly dissociative model. For example, Gonzalez et al. (2008) basing themselves on experimental data conducted with optical illusions and on observations in naturalistic contexts, they discovered that the visuomotor mechanisms encapsulated in the left hemisphere play a crucial role in the visual control of the action and that this specialization is independent of the fact that the (right-handed) subject use his right or left hand. If understanding language means coordinating fine articulations of sound with their meaning and producing language means organizing extremely complex fine movements to transform them into fine and extremely complex sounds, sounds of precision in a certain sense; similarly, precision gripping requires coordination of visual inputs with motor outputs. So Gonzales et al. (2006) showed that precision gripping for left-handed people is much more often right-handed than precision gripping is left-handed for righthanded people. Some studies are in line with this idea that lateralization optimizes function; the point is not so much in understanding whether the lateralization is to the right or to the left, but the degree of lateralization, i.e. how much a person has a marked tendency (whether it is to the right or to the left, it doesn’t matter). For example, individuals with strong lateralization for language appear to have a higher IQ than others (Everts et al. 2009) and better reading ability (Chiarello et al. 2009). In verbal dichotic listening tasks, the more lateralized a subject is, the better his or her performance will be (Hirnstein et al. 2014). Some observations and experimental studies conducted on patients with congenital deafness are consistent with this theoretical proposal in two directions: 1. On the one hand, in patients with unilateral deafness the cerebral reorganization is oriented towards an increase in the asymmetrical response, an indication that the subject pushes himself to optimize all the cerebral resources he has available to compensate for the sensory deficiency. 2. On the other hand, the difficulties of subjects with unilateral deafness are more marked if the hearing loss is on the right rather than on the left, this indicates that despite the compensations that the cultural and real life margin grants us - The phylogenetic inheritance favors the left hemisphere for linguistic tasks even in the absence of hearing from one of the two ears (Galletti et al., 2020).

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Relationship among Lateralization, Use of Hand and Language

Michael Corballis proposes a reconstruction of the phylogenetic origin of language which places the development of articulated language at the acme of a process of linguistic sophistication which is practically almost complete by now (Corballis, 2002). That is, in his reconstruction, the preparatory stages for the use of articulated language already seem to have contributed predominantly to the cognitive development linked to what we use to call language. The most important preparatory stage in this sense would have been the use of the hands to produce gestural protolanguages. One of the proofs that he brings in support of this demanding thesis is that, although the lateralization of intraspecific vocal calls is quite ancient (as indeed we have seen in § 7.2), the development of manual dominance in non-human primates is much scarcer than in humans (and we also confirmed this in §7.2.2). According to Corballis, the use of the hand for gestures led to a lateralization of manual movements: specifically, humans used, as indeed non-human primates still do, communicative vocalizations (not yet linguistic) lateralized to the left (as in rest of the primates). These vocalizations began to associate communicative gestures. The simultaneous and synchronized use of vocalizations and gestures (not yet lateralized) would have led to the lateralization of the latter: “when vocalizations were increasingly incorporated into manual gestures, a left-hand dominance could also have been determined for gestural communication. [. . .] Once gesture became associated with vocalization, it too may have lateralized” (Corballis, 2002 Synopsis). Corballis’s idea that (unsigned) gestural communication preceded language is acceptable and well supported by the reading on primates that he himself analyzes. Less convincing, however, is his idea that this protolanguage essentially constituted the linguistic turning point that is talked about so much when human uniqueness is sought, even if in several passages he himself seems to partially diminish the cognitive power of this first form of communication, so that in fact his position on the matter is not always very clear. But despite this, I find it interesting to deepen that aspect of his theory concerning the lateralization of the hand. Corballis in fact believes that the lateralization of the use of the hand has been accentuated precisely by virtue of the fact that it was also used by the first hominids for communicative purposes. This part of Corballis’ theory is supported by a study, which we have already mentioned in §7.3.3, published in 2006 by Taglialatela et al. in which the experimenters found that the brain area homologous to Broca’s area of some chimpanzees accustomed to gestural communication with hands (and tending to be right-handed) was larger than chimpanzees that did not use to communicate with hands. Indeed, I share the idea that the fact that intraspecific vocal communication has been left lateralized for a long time in phylogeny and hand dominance is so developed only in humans is a central element for the reconstruction of the phylogenetic history of language. However, the fact that manual dominance has been

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accentuated only because the hand has begun to be used for gestural communication goes against two phenomena: the first is that any gesture can be effective whether it is performed with the right hand or with the left, therefore there should be no evolutionary push towards the right hand, as there is in humans. The second phenomenon is that primates, as Corballis himself points out in the third chapter of his book, are quite accustomed to gestural communication, despite this, they do not show that propensity to the right typical of human beings. For example, mountain gorillas, skilled manipulators of objects, generally perform the finest manipulations with the right hand; however, if the right-handed proportion for gorillas is around two thirds of the animals observed (Byrne, 1996), in humans this percentage is significantly higher (Papadatou-Pastou et al., 2020). Chimpanzees, being skilled gesticulators, should show clear manual dominance, yet this - as we have seen - only partially occurs. So where does that other part of the link between linguistic lateralization and manual dominance that remains unexplained in Corballis’s theory come from? In my opinion, the possibility of manipulating an object while talking about has undoubtedly led to a sophistication of thought about it. Please imagine to talk about a pen while looking at it from a distance and then imagine to talk about the same pen while manipulating it. Which of the two situations enriches the thinking and the communication on the pen? Manipulation fosters creativity and technological thinking. As Corballis himself reports, Broca’s area, in addition to its linguistic functions, seems to play a role of primary importance also in the integration between hand movements and vision. However according to Corballis, this role has nothing to do with language (cfr. Corballis, 2002 ch. 3). Here again we find ourselves disagreeing with his opinion. The idea proposed here is that between the hand and language there is yet another link beyond the one identified by Corballis: the manipulation of the object we are talking about (or on which we are reflecting through language) becomes itself a form of (linguistic) thinking. This possibility of reflecting on the object while manipulating it is also at the basis of the evolution of technologies. Technologies have undoubtedly been more decisive in humans than in other species for adaptation to the environment. Corballis himself believes that technological progress is mostly due to the appearance of spoken language. If in order to reflect on an object I had to somehow bring to mind iconic (or even arbitrary and by now conventionalized) hand gestures, the manipulation of the same would probably creates phenomena of interference for me, limiting in some way the analyticity or the generativity of my thought. The possibility of separating the gestures of manipulation from the gestures of reflection (that is, the motor linguistic articulation, even silent, of the inner language), favors the depth of thought. In other words, if we reflect on the cognitive function of language, and not just on the communicative one, we immediately realize that the word allows us to think about the world while manipulating it. This would be incredibly more difficult if we had to think through hand signs. Not that the use of manual signs impedes creativity, but it is probably an obstacle to that type of performative creativity that we adopt

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when, manipulating an object, we reason about it. This activity, being at the basis of the creation of technological artefacts and their progressive complexification, has modified not only our knowledge in a direct way, but also our world, making it precisely - full of our technologies, which in turn further influence thinking (Clark & Chalmers, 1998). If this is the case, handedness may have lateralized because it has become part of linguistic reasoning. Manipulating an object and linguistically reasoning about it can be the same cognitive process. As Corballis himself points out, manipulation and communication have in common that they are not reactions to the environment, but manipulations of it: “Communication and manipulation could be considered operations on the environment rather than reactions to it” (Corballis, 2002:231) In this sense, the reflections of Brown and Magat (2011) on the systematic correlation found between the lateralization of the foot and the eye in parrots also come in handy: according to the researchers, the lateralization of the foot is a consequence of the side with which the animal is analyzing the object (therefore a consequence of the eye with which he is analyzing it). When human beings analyze an object, they don’t do it only visually, a huge component of the analysis of the object or of the reflection for the creation of the technology takes place linguistically, through an internal dialogue (even in the Vjgotskian sense) or a group dialogue if the creative act is collective. Linguistic symbols are elaborated by the left hemisphere and therefore in this the hand of choice for analytical reasoning would be the right hand. If intraspecific vocal communication was already tendentially lateralized to the right, it is plausible that gestural communication was too, at least to a prevalent extent. The Neanderthal had a large brain, had hands, these were probably already lateralized, but did not have the same articulation of the supralaryngeal vocal tract as homo sapiens (Corballis chapt 7). The contribution of the hand then was to provide a bodily substrate that already predisposed man to performative-analytical reasoning, but then with the development of a supralaryngeal vocal tract that allowed the phonetic expression we know today without excessive effort, we reached that definitive turning point that seems to have made us unique. The possibility of creating potentially infinite signifiers, thanks to a vocal tract capable of generating such complex and combinable articulated sounds, has allowed us to syncretize perceptual experiences in complex concepts. Language allows us to manipulate with the voice (even the inner voice, in the sense that we think with words), but this manipulation is infinitely more complex than that possible with the hands: behind the word “ball” all the complex representations of the ball are hidden that we have learned through manipulation; language allows for a great many physical experiences to be condensed under a single label and to be used cognitively together while continuing to experiment with the object. The phylogenetic and ethological data considered so far are in line with this idea, but it is also worth turning our gaze to children: during ontogenetic development, as we will see, the correlation between manipulative attitudes and language development is very strong.

8.7

8.7

Relationship Between Manipulation and Language during the. . .

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Relationship Between Manipulation and Language during the Ontogenetic Development

We will now try to show that during ontogenetic development, the manipulation of the object by the child greatly favors the growth of vocabulary. The reasons for this phenomenon will also be discussed. That the manipulation of objects by infants is a very important tool for understanding the world, as well as being rather intuitive, has also been expertly illustrated by many researchers. Holly Ruff, for example, in 1984, showed that from 6–9 months to 12, the exploration of objects with the mouth progressively becomes less and less important and is replaced by greater exploration through the fingers. Manipulation becomes increasingly intense when the child encounters specific characteristics of the object and progressively decreases when the child gets “used” to those characteristics, i.e. when they become familiar to him. The search for physical causality through the exploration of objects probably begins before the age of six months (Rakison & Krogh, 2012). Wilcox et al. (2007) experimentally showed that the formation of concepts around 10.5–11.5 months of age does not benefit from mere visual exposure to the object, it requires tactile as well as visual exploration. Indeed, motor skills, object manipulation skills, and conceptual knowledge of objects appear to progress hand in hand throughout child development (Soska et al., 2010; LeBarton & Iverson, 2016). Yu et al. (2009) showed that even if the infant’s communicative partner’s actions cause the infant to pay more attention to the object with which the two are interacting in a triadic relationship, the infant’s use of his own hands child is crucial for learning the concept. In their opinion, the fact that the child (or the adult) holds the object in his hand favors in a certain sense a cleaning of the perceptive setting due to the greater relevance that this assumes with respect to the context. Which happens with much greater difficulty if you point to an object in the distance without interacting with it. More recently, Slone et al. (2019) placed an eye-tracker on the head of 15-monthold infants, observing their visualizations while manipulating objects. Well, they found without any doubt that the child’s tendency to manipulate the object more, creating ever-changing angles of view of the object, predicted a much greater growth of vocabulary in the following six months than that which occurred in children who explored minus the object. With a similar methodology James et al. (2014) studied the relationship between the manipulative-exploratory behavior and the linguistic behavior of 18–24 months old children, finding that the tendency of children to move objects in such a way as to be able to observe their (naturally unusual) planar perspective was positively correlated to the growth of their vocabulary and also to their ability to recognize 3D representations of geometric shapes. The manipulation of an object for exploratory purposes is therefore strongly correlated with the growth of vocabulary; despite that-however-this doesn’t always happen with the same hand. In principle, it is possible to classify children on the basis of the preference for the use of the manipulative hand like adults (right-handed,

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left-handed, ambidextrous). Well, Vauclair and Imbault (2009) found that the propensity towards the use of one hand over the other or the absence of a preference in the manipulation of objects is not related to the preference of using the hand for communicative gestures, as - regardless of the manipulative dominance - children tend to use the right hand for the production of pointing gestures. Taken together, these data provide support for our idea: the hand in the human being allows an exploration of the world that favors its analytical study. This possibility of analysis, combined with that of using a multiplicity of phonemes to create potentially infinite signifiers, transforms into a cognitive enhancement without equal in the animal world. We have seen that the bimanual manipulation of objects that requires coordinated use of the hands is linked to a lateralization of the function and that it corresponds to a functioning asymmetry of the primary motor cortex which usually favors the left hemisphere (right hand). The phylogeny also favors the left lateralization of the communicative gesture. But the existence of right-handed right-lateralized speech and left-handed left-handed speech clearly shows that the two systems developed independently. But how to explain the high percentage of right-handed people lateralized to the right for language? As we tried to explain in § 7.6, the manipulation of objects, associated with a certain type of analytical thinking, is realized in man through the use of an inner dialogue. In man, part of thought is also a dialogue with himself, i.e. a communicative behavior directed towards himself or towards the conspecifics present during manipulation. In humans, therefore, the manipulation of an object can be associated with a dialogical thought directed towards the subject himself who manipulates or the community present during the manipulation of the object. In humans, thought and language are two highly overlapping cognitive processes.

8.8

Sign Languages: Differences Between the Ontogenetic Plane and the Phylogenetic Plane

One of the criticisms that could be leveled against this theory is that sign languages are languages in all respects as they have all the characteristics that we usually attribute to languages: semantic omnipotence, productivity, metalinguistics, arbitrariness, iconicity, etc.. . . (Cavalieri, 2022). The acquisition of this awareness has had a tormented history (see Chiricò, 2014), but it is not now questioned by scientific thought. Signers are not second-choice thinkers, not only - as we shall see - they show cognitive performances usually similar to those who speak with the voice, but their cognitive peculiarities sometimes provide them with advantages. For example, it has recently been demonstrated that some difficulties of the deaf sometimes encountered in reading are to be attributed rather to the need to use a less ergonomic language for them than to cognitive difficulties related to working memory or executive functions (Deng & Tong, 2021). In fact, the neuroanatomical

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areas for lexical retrieval are similar between signers and non-learners (Emmorey et al., 2003). Or again, the category sensitivity found by N170 activation is preserved in deaf signers (Mitchell, 2017). Among other things, deaf signers perform better in facial recognition tasks than normal hearing ones (Bettger et al., 1997; McCullough & Emmorey, 1997) and this does not depend on their deafness condition, but specifically on their experience with sign language (Bettger et al., 1997). Indeed, it seems that if, during face recognition, hearing people activate the fusiform gyrus bilaterally, in signing deaf people there is a lateralization of the function (only the left fusiform gyrus is activated) and this probably because face recognition, taking place during linguistic reception, becomes part of the linguistic process (McCullough et al., 2005). Another cognitive advantage associated with the use of signed languages concerns attention and visual discrimination: deaf signers can retain short-term and long-term visual information more accurately than normal hearing people (Craig et al., 2022). Furthermore, signers are better than hearing impaired both in visual rotation tasks and in the memory of the spatial orientation of objects (Emmorey et al., 1998). However, signers live in an oral world, that is, in a world in which those who can hear - in all cultures - prefer oral communication. As we have just seen, the advantage of the linguistic sign compared to the manual sign is not to be understood at an ontogenetic level, but only at a phylogenetic level: the first hominids will certainly have been advantaged by the absence of cognitive interference phenomena between signifiers and manipulative gestures during creation of those technologies that have served them to defend themselves from predators physically much more gifted than them; just as they certainly benefited from the possibility of communicating with each other in the dark or communicating while they were intent on collective activities that required the use of their hands such as hunting or fruit picking; they will also have benefited from the possibility of communicating remotely in the presence of obstacles to sight.

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Chapter 9

Conclusions

The book started from an apparently circumscribed question: “what role do the eyes play in human communication?”. Indeed, the attempt to answer this question exhaustively has unexpectedly confirmed the veracity of Kant’s affirmation that all philosophical questions can ultimately be traced back to a single - perhaps aporetic question: what is man? (Kant et al. 1988). It is common to most human beings to evaluate a person’s sincerity by looking carefully into his eyes; likewise, that of having looked into a person’s eyes in order to communicate the absolute sincerity and/or depth of feeling associated with the information transmitted with other forms of communication. Literature and cinematography have also partially sanctified, dare I say, this perception. In the West (and perhaps not only) the common idea is that the eyes are the mirror of the soul. The recent discovery that the ocular configuration of man is another anatomical feature that makes us unique in the animal kingdom has led some theorists to imagine a role for this feature in the phylogenetic development of language: we have always been told that the human being is special in comparison to other animals because it speaks; couldn’t it also be special because it instantly transmits its mental life to other conspecifics through its eyes? In order to test the effective influence of communication through looks in the most intimate constitution of the human species, we proceeded with a comparative analysis of the ethological literature. In fact, with this system no significant structural differences were found in the use of gazes between humans and other animals. Following this, an attempt was even made to show that the differences in the use of gazes between us and non-human primates are the result of the communicative habit of the species and are all in all the result of the cognitive differences between humans and other primates: man has developed articulate language, which has led to the development of peculiar mental structures (which, for example, allow the recurrence of thought) and consequently communication through looks has taken on some peculiar characteristics (such as, for example, the habit of what Tomasello defined as ‘double gaze’). The one human peculiarity which seemed to me to have truly no phylogenetic precedent approaching it (and which strangely is systematically © The Author(s), under exclusive license to Springer Nature Switzerland AG 2023 P. Pennisi, Gazes, Words, and Silences in Pragmatics, Perspectives in Pragmatics, Philosophy & Psychology 36, https://doi.org/10.1007/978-3-031-42571-4_9

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overlooked by perspectives which aim to somehow link peculiarities in communication through gazes with language development) is the presence of emotional tears. Emotional tears have been configured in our eyes as a sort of compensatory tool: given that man can lie with language, tears serve to seal the sincerity of the information they accompany. But even here, I seemed to see a dependence (and an adaptation) of the communicative system mediated by looks on the cognitive structure linked to language: it is precisely the systematic possibility of lying that requires a system of attestation of sincerity for emergencies (i.e. those that are emotionally salient and generally cause emotional tears that are important to be trusted). After excluding that the phylogenetic (and ontogenetic) development of language may depend in some way on the anatomy of the human eye, we have attempted to outline the bodily phylogenetic precursors which may instead have constituted the trigger for the virtuous process of language. In this way it has been hypothesized that it is the co-presence of a supralaryngeal vocal tract that allows the production of articulated sounds and of a hand capable of producing subtle manipulations of the world while, through the system of oral signifiers, one reflects on these to have the cognitive turning point for the genus homo. The book concludes by trying to show that the data we have available today on the lateralization of manual skills and oral communication seem compatible with the proposed perspective, as they show that the two processes are not strictly dependent (in fact, all four combinations are present in human species: linguistic left lateralization, right hand dominance; linguistic left lateralization, left hand dominance; linguistic right lateralization, right hand dominance, linguistic right lateralization, left hand dominance). However, there is a clear preference for the first combination; which translates, at the cerebral level, with a preference of the left hemisphere for the management of both processes. The fact that the two processes are independent, but linked to the same lateralization causality laws is in line with our idea that the hand and the articulate speech are two independent but complementary body systems that allow us to reflect on the external world (through the physics and linguistics manipulation) simultaneously from two routes; generating that thought power typically associated with human language; as well as that ability to modify the external world and to create technologies external to the body necessary for the fitness of the species.

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