Abstract
Race refers to the socially constructed classification of human faces based on salient physical traits. This biologically relevant feature is extracted automatically, almost instantly and markedly shapes face processing. Previous studies have shown that observers recognize more accurately same- (SR) than other-race (OR) faces (i.e., the Other-Race Effect - ORE), but categorize them more slowly by race (i.e., the Other-Race Categorization Advantage - ORCA). While several fMRI studies reported stronger neural activations to the recognition and categorization of SR vs. OR faces in the Fusiform Face Area (FFA) and Occipital Face Area (OFA), others reported discrepant findings. Interestingly, stronger activations in these face-sensitive regions were also often associated with greater magnitude of ORE and ORCA. However, whether these face-sensitive regions play a genuine causal role in the other-race effects remains unknown. To clarify this issue, we tested PS, a pure case of acquired prosopagnosia with bilateral occipitotemporal lesions encompassing the left FFA and the right OFA. PS, healthy age-matched and young adults performed two recognition and three categorization by race tasks, using different databases of normalized Western Caucasian and East Asian faces with, without external features and in naturalistic settings. As expected, our data show superior memory performance but slower categorization responses for SR than OR faces in controls, with PS having slower and less accurate responses. Crucially, however, the magnitude of PS’ ORE and ORCA was comparable to the controls in all the tasks. Our data show that an intact face-cortical network – and more precisely intact left FFA and/or right OFA – is not causally necessary to observe the other-race effects. These brain regions therefore only boost the accuracy and speed of those effects. Race is a strong visual and social signal that is encoded in a large neural face-sensitive network, robustly tuned for processing same-race faces.