Reward, affiliation, and dominance smiles communicate different social motives following trust violations

Others’ facial expressions can influence whether we trust them. For example, smiles tend to elicit positive impressions and increased cooperation. But how are smiles perceived when displayed by someone who has violated our trust? Here, we investigated the effects of reward, affiliation, and dominance smiles displayed after intergroup trust violations. In four studies, participants representing a group played an economic game with a representative of another group. In an initial round, this representative breached trust by favouring her group and displayed a reward, affiliation, or dominance smile in relation to this decision. Participants rated the motives communicated by the representative and then played a second round of the game with a different outgroup member. Smiles displayed by the representative had distinct effects on participants’ judgments: affiliation smiles following trust violations communicated less positivity and superiority, and greater desire to repair the relationship between groups and to change the unfair decision than reward or dominance smiles. Moreover, perceptions of willingness to repair the relationship and to change the decision predicted trust and cooperation in the second round of the game. Taken together, these findings document the diversity of messages conveyed by smiles and the importance of context in interpreting these expressions.