Smiles when sharing

One of the proposed functions of human smiling is to advertise cooperative dispositions and thereby increase the likelihood that a social partner would invest resources in a relationship. In particular, smiles involving an emotional component would be honest signals of altruistic dispositions because they are not easy to produce voluntarily. In this study, 60 people were covertly filmed while interacting with a friend in two conditions: control and sharing. Smiles were classified into Duchenne (spontaneous) and non-Duchenne smiles. Participants also completed a series of questionnaires, including the Altruism Scale and a self-report questionnaire of emotional state. Interestingly, Duchenne smiles were displayed at higher rates in the sharing situation as opposed to the control situation, whereas non-Duchenne smiles were unaffected by the type of interaction. Furthermore, Duchenne smiles in the sharing interaction were positively affected by a measure of altruism. Self-reported emotional states did not vary between conditions and were poorly related to smiling. This study shows that the Duchenne smile is relevant to situations that involve the sharing of material resources because it would reliably advertise altruistic intentions. The Duchenne smile could therefore be an important signal in the formation and maintenance of cooperative relationships.

[1]  R. Andrew,et al.  EVOLUTION OF FACIAL EXPRESSION. , 1963, Science.

[2]  Chris Moore,et al.  Are there Nonverbal Cues to Commitment? An Exploratory Study Using the Zero-Acquaintance Video Presentation Paradigm , 2003 .

[3]  Karen L. Schmidt,et al.  Human facial expressions as adaptations: Evolutionary questions in facial expression research. , 2001, American journal of physical anthropology.

[4]  Catherine C. Eckel,et al.  The Value of a Smile: Game Theory with a Human Face , 2001 .

[5]  B. Thierry,et al.  Structural convergence between silent bared-teeth display and relaxed open-mouth display in the Tonkean macaque (Macaca tonkeana). , 1989, Folia primatologica; international journal of primatology.

[6]  Robin I. M. Dunbar.  The Human Story , 2004 .

[7]  P. Ekman,et al.  Felt, false, and miserable smiles , 1982 .

[8]  Robin I. M. Dunbar,et al.  Differential Behavioural Effects of Silent Bared Teeth Display and Relaxed Open Mouth Display in Chimpanzees (Pan troglodytes) , 2005 .

[9]  R. Hinde.  Chapter 5 – Expression and Negotiation , 1985 .

[10]  Peter Hammerstein,et al.  Genetic and cultural evolution of cooperation , 2003 .

[11]  R. Trivers.  The Evolution of Reciprocal Altruism , 1971, The Quarterly Review of Biology.

[12]  F. D. de Waal,et al.  The formal hierarchy of rhesus macaques: An investigation of the bared‐teeth display , 1985, American journal of primatology.

[13]  O. Petit,et al.  Affiliative function of the silent bared-teeth display in moor macaques (Macaca maurus): Further evidence for the particular status of sulawesi macaques , 1992, International Journal of Primatology.

[14]  J. Krebs,et al.  Behavioural Ecology: An Evolutionary Approach , 1978 .

[15]  J. Bachorowski,et al.  Reconsidering the Evolution of Nonlinguistic Communication: The Case of Laughter , 2003 .

[16]  R. Frank.  Passions Within Reason: The Strategic Role of the Emotions , 1990 .

[17]  B. Depaulo,et al.  Nonverbal behavior and self-presentation. , 1992, Psychological bulletin.

[18]  J. P. Rushton,et al.  The altruistic personality and the self-report altruism scale , 1981 .

[19]  M. Argyle.  Bodily communication, 2nd ed. , 1988 .

[20]  Judith Latta Hand,et al.  Resolution of Social Conflicts: Dominance, Egalitarianism, Spheres of Dominance, and Game Theory , 1986, The Quarterly Review of Biology.

[21]  A. J. Fridlund.  Human Facial Expression: An Evolutionary View , 1994 .

[22]  John Dupré,et al.  The Latest on the best : essays on evolution and optimality , 1987 .

[23]  M Mehu.  An evolutionary approach to human social behaviour : the case of smiling and laughing. , 2006 .

[24]  F. D. de Waal.  The integration of dominance and social bonding in primates. , 1986, The Quarterly review of biology.

[25]  F. Waal,et al.  The Communicative Repertoire of Captive Bonobos (Pan Paniscus), Compared To That of Chimpanzees , 1988 .

[26]  J. Hirshleifer.  On the Emotions as Guarantors of Threats and Promises , 1984 .

[27]  Klaus Atzwanger,et al.  New Aspects of Human Ethology , 2013, Springer US.

[28]  Chris Moore,et al.  Smile asymmetries and reputation as reliable indicators of likelihood to cooperate: An evolutionary analysis , 2002 .

[29]  Joseph P. Forgas,et al.  On feeling good and getting your way: mood effects on negotiator cognition and bargaining strategies. , 1998, Journal of personality and social psychology.

[30]  J. Altmann,et al.  Observational study of behavior: sampling methods. , 1974, Behaviour.

[31]  L. Parr,et al.  Muscles of facial expression in the chimpanzee (Pan troglodytes): descriptive, comparative and phylogenetic contexts , 2006, Journal of anatomy.

[32]  A. Columbus.  Advances in Psychology Research , 2005 .

[33]  Joan B. Silk,et al.  3 Cooperation without Counting The Puzzle of Friendship , 2003 .

[34]  V. Hooff.  A comparative approach to the phylogeny of laughter and smiling. , 1972 .

[35]  Stephen Bochner,et al.  Cross-cultural assessment of altruism and its correlates , 1989 .

[36]  A. Dixson.  Observations on the displays, menstrual cycles and sexual behaviour of the “Black ape” of Celebes (Macaca nigra) , 2009 .

[37]  Van Hooff,et al.  The Facial Displays of the Catarrhine Monkeys and Apes. , 1967 .

[38]  Martin Fieder,et al.  THE COMMUNICATION PARADOX AND POSSIBLE SOLUTIONS Towards a Radical Empiricism , 1997 .

[39]  Robin I. M. Dunbar.  Primate social systems , 1987 .

[40]  Signe Preuschoft,et al.  The social function of "smile" and "laughter": Variations across primate species and societies. , 1997 .

[41]  R. Dawkins,et al.  Animal signals: information or manipulation? , 1978 .