The role of surface and shape information in the other-race face effect

Both shape and surface dimensions play an important role in face (e.g. O'Toole et al., 1999) and race recognition (Hill et al., 1995). However, the relative contribution of these cues to other-race (OR) face recognition has not been investigated. Some facial properties may be diagnostic in one race but not in the other (e.g. Valentine, 1991). Observers of different races would rely on facial cues that are diagnostic for their own-race faces, a phenomenon which could partly explain our relative difficulty at recognizing OR faces at the individual level (the so-called other-race effect). Here, we tested this hypothesis by examining the relative role of shape and surface properties in the other-race effect (ORE). For this purpose, we used Asian and Caucasian faces from the MPI face database (Vetter Blanz, 1999) so that we could vary both shape and surface information, only shape information (in which the surface texture was averaged across individual faces of the same race), or only surface information (in which shape was averaged). The ORE was measured in Asian and Caucasian participants using an old/new recognition task. When faces varied along both shape and surface dimensions, Asians and Caucasians showed a strong ORE (i.e. a better recognition performance for same- than other-race faces). With faces varying along only shape dimensions, the ORE was no longer observed in Asians, but remained present in Caucasians. Finally, when presented with faces varying only along surfacedimensions, the ORE was not found for Caucasians whereas it was present in Asians. These results suggest that the difficulty in recognizing OR faces for Asian observers can be partly due to their inability to discriminate among surface properties of OR faces, whereas ORE for Caucasian participants would be mainly due to their inability to discriminate among shape cues of OR faces