Abstract
Individuals can be exposed to very different diets of faces depending on where they live and their social environment, and these stimulus differences are thought to shape their perception of faces through processes including adaptation and learning. We explored variability in face percepts by comparing face categorization judgments for the same face images for adults in Tokyo, Japan or Reno, Nevada. Stimuli were morphs between 4 pairs of averaged faces differing in gender (female vs. male) or nationality (Japanese or Swiss). Observers classified different levels of the morphs according to the 4 different categories, with the category boundary and sensitivity estimated from probit fits to the psychometric functions. For both the gender and ethnicity judgments, the overall mean boundaries and sensitivity were similar across the two locations and regardless of the respondents’ gender. In contrast, individual differences within each group were very large, and substantially greater than the within-subject variability (estimated from repeated measurements). These individual differences also showed moderate correlations across some of the pairs (e.g. covarying ethnicity boundaries for male or female pairs). Similarities across the groups could not be accounted for by within-session adaptation or range effects for the face arrays, because for two pairs the categories were strongly skewed toward one of the original faces in the morph. For the conditions of these studies, the results instead suggest that cross-cultural factors may exert relatively limited influence compared to factors that determine an individual’s face categories, a pattern reminiscent of individual and population differences in color categories.