Categorical effects in the perception of faces

TLDR

Categorical perception effects appear to be more general than previously thought, occurring across diverse processing levels. The study aimed to examine how individual face representations are organized by creating a linear continuum of morphed faces between familiar exemplars. Participants performed categorization, discrimination, and better‑likeness tasks on face pairs drawn from these continua to probe perception. Accuracy was highest when face pairs crossed category boundaries, and the size of the categorization effect correlated strongly with familiarity, indicating that categorical perception extends to higher‑level face representations and can be shaped by experience.

Abstract

These studies suggest categorical perception effects may be much more general than has commonly been believed and can occur in apparently similar ways at dramatically different levels of processing. To test the nature of individual face representations, a linear continuum of "morphed" faces was generated between individual exemplars of familiar faces. In separate categorization, discrimination and "better-likeness" tasks, subjects viewed pairs of faces from these continua. Subjects discriminate most accurately when face-pairs straddle apparent category boundaries; thus individual faces are perceived categorically. A high correlation is found between the familiarity of a face-pair and the magnitude of the categorization effect. Categorical perception therefore is not limited to low-level perceptual continua, but can occur at higher levels and may be acquired through experience as well.