Face the difference: Metacontrast as an affordance to spontaneous social categorization

Humans readily categorize their social environment based on visible features regarded as diagnostic for group membership (e.g., skin color, hair color, body morphology) along lines of various social dimensions, including gender, race, age, to name just a few. Despite overwhelming evidence for the notion that these dimensions can be used to bring categorical order into the world, psychologists know surprisingly little about what determines which of these lenses is active in a given moment. The present research examines whether ecological metacontrast provides an affordance to social categorization and selective category use. Across seven studies (N = 1,234), we manipulated metacontrast ratios by varying the dispersion of race- and gender-related facial features to examine their effects on spontaneous social categorization. Categorization was assessed using the "Who Said What?" paradigm (Taylor et al., 1978), with categorization parameters estimated via multinomial processing tree models (Klauer & Wegener, 1998) and a Speeded Categorization task (Thomas et al., 2014). Participants consistently categorized faces by race (Studies 1a, 2a) and gender (Studies 1b, 2b), regardless of metacontrast ratio. However, when race and gender were crossed (Studies 3-5), significant interaction effects emerged: categorization along the low metacontrast dimension decreased, while it increased along the high metacontrast dimension. These findings provide initial evidence that metacontrast modulates the relative accessibility of social categorizations. The distribution of category-related features within a social information ecology thus provides affordance to some categorizations more readily than others. Study-specific patterns related to stimuli and task constraints are discussed to inform future research. (PsycInfo Database Record (c) 2026 APA, all rights reserved).