Beyond mere novelty: Categorization drives differentiation

Abstract Stereotype formation is shaped by differentiation , that is, the tendency to prioritize attributes that render a novel group distinct from comparison groups. While differentiation is well documented, it remains unclear whether it is intrinsic to categorization or whether it is a byproduct of a general processing advantage of novel stimuli. We conducted three preregistered experiments to disentangle these accounts. In all experiments, participants learned a set of social traits that were either assigned to a single group or distributed across two groups. Crucially, novel traits presented in the second half of the stimulus set marked intergroup distinctiveness only in the two‐groups condition while being equally novel in the single‐group condition. In line with a category‐based account of differentiation, recall for novel traits was enhanced in the two‐groups condition compared to the single‐group condition (Exp. 1 & 3) and an additional control condition without groups (Exp. 3). Moreover, novel traits were judged as more typical for their group than initially learned traits, but only in the two‐groups condition (Exp. 2). These findings suggest differentiation is not a fixed response to novelty but a genuine categorization effect, serving a functional role in distinguishing groups. We discuss implications for category learning and stereotype formation.