Congenital prosopagnosia, an innate impairment in recognizing faces, as well as the other-race-effect, the disadvantage in recognizing faces of foreign races, both influence face recognition abilities. Here we compared both phenomena by testing three groups: German congenital prosopagnosics (cPs), unimpaired German, and unimpaired South Korean participants (n = 23 per group), on three tests with Caucasian faces. First we ran the Cambridge Face Memory Test (Duchaine & Nakayama, 2006 Neuropsychologia 44 576–585). Participants had to recognize Caucasian target faces in a 3AFC task. German controls performed better than Koreans (p = .009) who performed better than prosopagnosics (p = .0001). Variation of the individual performances was larger for cPs than for Koreans (p = .028). In the second experiment, participants rated the similarity of Caucasian faces (in-house 3D face-database) which differed parametrically in features or second order relations (configuration). We found differences between sensitivities to change type (featural or configural, p = 0) and between groups (p = .005) and an interaction between both factors (p = .019). During the third experiment, participants had to learn exemplars of artificial objects (greebles), natural objects (shells), and faces and recognize them among distractors. The results showed an interaction (p = .005) between stimulus type and participant group: cPs where better for non-face stimuli and worse for face stimuli than the other groups. Our results suggest that congenital prosopagnosia and the other-race-effect affect face perception in different ways. The broad range in performance for the cPs directs the focus of our future research towards looking for different forms of congenital prosopagnosia.
