Partner’s Gaze with Duchenne Smile in Social Interaction Promotes Successive Cooperative Decision

Abstract

Smile has been conceptualized as a signal of cooperative intent. However, given that smile is easy to fake, how smiling conveys the cooperative intention has long been a question of great interest. Although previous work suggests that people tend to mimic other’s smile and interpersonal synchrony is linked to prosocial behaviors, how synchronized smiling will influence cooperation is yet to be studied. What’s more, the impact of gaze direction during smiling on prosocial outcomes is still unclear. The authors investigated gaze direction and synchronized smiling across the course of 5-min conversation among pairs of same-sex strangers, and cooperation in a one-shot, two-person Prisoner’s Dilemma game occurring directly following the conversation. Consistent with previous works, Duchenne smiling predict their cooperation of the receiver in the Prisoner’s Dilemma game. It was found that greater direct gaze during synchronized Duchenne smiling predicts greater likelihood of cooperation by both the signaler and the receiver in the prisoner’s dilemma game. The results indicate that the Duchenne smiling with direct gaze may be an honest signal of cooperative intent.