Healthy Out-Group Members Are Represented Psychologically as Infected In-Group Members

A range of studies have demonstrated that people implicitly treat out-groups as the carriers of pathogens and that considerable prejudice against out-groups is driven by concerns about pathogens. Yet the psychological categories that are involved and the selection pressures that underlie these categories remain unclear. A common view is that human pathogen-avoidance psychology is specifically adapted to avoid out-groups because of their potentially different pathogens. However, the series of studies reported here shows that there is no dedicated category for reasoning about out-groups in terms of pathogens. Specifically, a memory-confusion experiment conducted with two large-scale samples of Americans (one nationally representative) yielded strong, replicable evidence that healthy out-group members are represented using the same psychological category that is used to represent manifestly infected in-group members. This suggests that the link between out-group prejudice and pathogen concerns is a by-product of general mechanisms for treating any unfamiliar appearance as an infection cue.