Examining the accuracy of lay beliefs about the effects of personality on prosocial behavior

Prior research on personality and prosocial behavior has focused on actor-level effects of personality by examining which personality traits predict individuals' prosocial behavior. But do lay people take into account others' personality when making predictions of others' future prosocial behavior? The present research was designed to answer this question. We focused on two interpersonal traits from the Big Five model, agreeableness and extraversion, and examined whether people have accurate lay beliefs about the effects of these traits on prosocial behavior. The results of four studies showed that participants consistently attributed agreeableness (and to a lesser extent, extraversion) a greater role in predicting others' prosocial behavior compared with the role that it plays in reality. Results were consistent in studies of zero-acquaintance interactions and close relationships and when people predicted both single instances and aggregated measures of others' prosocial behavior. Our results did not depend on participants' awareness of research hypotheses and persisted even when they were explicitly warned that the information about others' personality might not be accurate. These findings inform the literature on social perception and stereotype accuracy and contribute to our understanding of how people make future-oriented predictions of others' behavior.