Proceedings of the Annual Meeting of the Cognitive Science Society

People often perceive their in-groups as more heterogeneousthan their out-groups. We propose an information samplingexplanation for this in-group heterogeneity effect. We analyzea model in which an agent forms beliefs and attitudes aboutsocial groups from her experience. Consistent with robust evi-dence from the social sciences, we assume that people are morelikely to interact again with in-group members than with out-group members. This implies that people obtain larger sam-ples of information about in-groups than about out-groups. Be-cause estimators of variability tend to be right-skewed, but lessso when sample size is large, sampled in-group variability willtend to be higher than sampled out-group variability. This im-plies that even agents that process information correctly – evenif they are naive intuitive statisticians – will be subject to thein-group heterogeneity effect. Our sampling mechanism com-plements existing explanations that rely on how informationabout in-group and out-group members is processed.