Out-group homogeneity bias

Biological Parallel

Chimpanzees readily distinguish individual faces within their own troop but struggle to differentiate members of neighboring communities, treating out-group chimps as interchangeable threats. This perceptual asymmetry evolved because fine-grained discrimination of in-group members enables coalition navigation and reciprocity tracking, while out-group members primarily matter as categorical dangers. The bias persists in human cross-race face recognition—we inherited neural architecture optimized for discriminating familiars, not strangers.