SOCIAL CATEGORIZATION AND PERCEPTUAL JUDGMENT OF SIZE - WHEN PERCEPTION IS SOCIAL

Social knowledge may affect not only people's thoughts and judgments b ut also their actual perceptions of physical magnitude. The physical m agnitude of a stimulus is perceived in a relative way, comparing the m agnitude of the target with surrounding context stimuli. Because simil ar objects invite comparison processes more easily than dissimilar obj ects (''similarity breeds comparability''), social knowledge can affec t judgments of physical magnitude by determining what is perceived as (dis)similar. In Experiment 1, the authors show that social categoriza tions that are based on physical cues (e.g., gender) may affect the ma gnitude of perceptual contrast effects (the Ebbinghaus illusion). More important, in Experiment 2, the influence of social categorizations t hat have no physical bases is shown to affect the magnitude of percept ual contrast effects. Implications of these findings for theories of s ocial knowledge effects are discussed.