Face familiarity, distinctiveness, and categorical perception

Abstract

Four experiments with faces support the original interpretation of categorical perception (CP) as only present for familiar categories. Unlike in the results of Levin and Beale (2000), no evidence is found for face identity CP with unfamiliar faces. Novel face identities were shown to be capable of encoding for immediate sorting purposes but the representations utilized do not have the format of perceptual categories. One possibility explored was that a choice of a distinctive face as an end-point in a morphed continuum can spuriously produce effects that resemble CP. Such morphed continua provided unequal psychological responses to equal physical steps though much more so in a better likeness paradigm than for forced-choice recognition. Thus, researchers doing almost the same experiments may produce very different results and come to radically different conclusions.

Notes

¹ In response to a reviewer's request, assessment of typicality was also examined for an Italian population. The three faces were given in a balanced order to 18 Italian students and to a corresponding new group of 18 UK students. Both groups were asked to give typicality ratings to the three faces under the same instructions as those in the main study. A Group (English vs. Italian) × Face (T1 vs. T2 vs. D) revealed only a main effect of face, F(2, 68) = 21.57, p < .0001. Paired t tests revealed that the effect was entirely due to the distinctive face (rating 4.89) being rated higher than face T1 (rating 3.22) or face T2 (rating 3.36) with ps < .0001 in both cases. T1 did not differ from T2 (t < 1). The range of typicality ratings is reduced compared to the faces being seen within a larger group but clearly both groups see the D face as being more distinctive to an equal extent.