Blurred Boundaries: A New Measure of Implicit Categorical Perception

Biologically, the physical features (e.g., skin tone, hair color) associated with racial groups vary continuously, yet people treat these socially constructed groups categorically. Do such categories affect how we /perceive /people, such that differences within category boundaries are difficult to perceive while differences across boundaries are accentuated? Do people differ in the degree of categorical race perception, and are there individual differences that predict this perceptual tendency? We developed a method for measuring implicit social categorization by examining confusion patterns among digitally morphed faces. Using hierarchical linear modeling, we found that participants demonstrated a reliable "categorical" pattern in their confusion rates, but that people differed in the strength of this pattern. We also examined potential predictors of implicit categorical race perception, such as participants' explicit racial labels for biracial celebrities, beliefs about genetic variation, and political ideology.