Stereotyping to infer group membership creates plausible deniability for prejudice-based aggression.

In the present study, participants administered painful electric shocks to an unseen male opponent who was either explicitly labeled as gay or stereotypically implied to be gay. Identifying the opponent with a gay-stereotypic attribute produced a situation in which the target's group status was privately inferred but plausibly deniable to others. To test the plausible deniability hypothesis, we examined aggression levels as a function of internal (personal) and external (social) motivation to respond without prejudice. Whether plausible deniability was present or absent, participants high in internal motivation aggressed at low levels, and participants low in both internal and external motivation aggressed at high levels. The behavior of participants low in internal and high in external motivation, however, depended on experimental condition. They aggressed at low levels when observers could plausibly attribute their behavior to prejudice and aggressed at high levels when the situation granted plausible deniability. This work has implications for both obstacles to and potential avenues for prejudice-reduction efforts.