Transcranial direct current stimulation (tDCS) eliminates the other‑race effect (ORE) indexed by the face inversion effect for own versus other‑race faces

Abstract

We investigate here individuals’ reduced ability to recognise faces from other racial backgrounds, a robust phenomenon named the other-race effect (ORE). In this literature the term “race” is used to refer to visually distinct ethnic groups. In our study, we will refer to two of such groups: Western Caucasian (also known as White European) and East Asian e.g., Chinese, Japanese, Korean. This study applied the tDCS procedure (double-blind, 10mins duration, 1.5mA intensity, targeting Fp3 location), we have developed in the perceptual learning literature, specifically used to remove the expertise component of the face inversion effect (FIE), which consists of higher recognition performance for upright than inverted faces. In the tDCS-sham condition (N=48) we find a robust ORE i.e., significantly larger FIE for own vs other-race faces due to higher performance for upright own-race faces. Critically, in the anodal-tDCS condition (N=48) the FIE for own-race faces was significantly reduced compared to sham due to impaired performance for upright faces thus eliminating the cross-race interaction index of the ORE. Our results support the major role that perceptual expertise, manifesting through perceptual learning, has in determining the ORE indexed by the FIE.