Can people combine various sources of information when forming impressions of others? Past social cognition research identified two broad information types used during impression formation: individuating and categorical (stereotype) information. Individuating information is about specific individuals’ past behaviours or hobbies. Stereotype information is about one’s social or demographic classifications like race or age. I aimed to move beyond this traditional distinction –– which assumed stereotype information to be the base rate –– by exploring if both information types can be used within a Bayesian framework (see McCauley & Stitt, 1978). Across two experiments, I presented categorical information only vs. categorical and individuating information together. Results suggested people’s judgements were less aligned with Bayes’ theorem when given social categorical information only than when given both, categorical and individuating information together (N = 1130). Broadly, this project aimed to link impression formation work with the larger literature on Bayesian decision-making in cognitive psychology.
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