Facial disfigurement, categorical perception, and the influence of Disgust Sensitivity

Previous research supports the categorical perception of faces on dimensions including emotion, identity, and gender. Two experiments using standard paradigms investigated whether facial disfigurement forms another perceptual category. In the Identification task, faces were presented in varying degrees of disfigurement for a simple disfigured / non-disfigured decision. As degree of disfigurement increased, the percentage of participants defining each image as disfigured increased non-linearly such that a cubic curve provided the best fit to the data, consistent with categorical perception (Experiment 1 and 2). In the ABX task, participants displayed superior discrimination between two faces when they crossed the category boundary between non-disfigured and disfigured (Experiment 1 and participants low in Disgust Sensitivity in Experiment 2). Participants high in Disgust Sensitivity (Experiment 2) showed a pattern that suggested the category boundary was shifted towards earlier perception of disfigurement. Overall, the results suggest categorical perception of facial disfigurement.