Are You Laughing at Them or with Them? Laughter as a Signal of In-Group Affiliation

Despite the wide range of theoretical explanations for human laughter, it is generally agreed to function, at least in part, as a social signal. We tested the hypothesis that laughter serves as a signal of group affiliation. Participants viewed a video clip depicting a confederate partner of unknown group affiliation displaying either a neutral expression, a smile, or laughter in response to a joke told at the expense of a member of the in-group or the out-group. Participants then decided whether to help the confederate in a fictional and incentivized economic game. When viewed in response to a joke told at the expense of the in-group member, participants were less likely to help after viewing the laughter clip in comparison to the neutral and smiling clips. However, when viewed in response to a joke told at the expense of the out-group member, participants were more likely to help after viewing the smiling clip in comparison to the neutral and laughter clips. Taken together, these findings suggest that laughter may serve to signal affiliation, albeit only among out-group members.