Abstract
Modern societies are multicultural and multiracial. Race is a visual signal transmitted by faces used for the early categorization of ingroup/outgroup members, strongly modulating their identification and social processing. However, whether the effect of race might also have an influence on action control, particularly on the executive function of action inhibition, has not been investigated yet. To this aim, Western Caucasian observers performed a Stop-Signal Task (SST) where they were instructed to inhibit their actions in response to faces. Stop signals were African-American (AA), Eastern-Asian (EA) and Western-Caucasian (WC) faces normalized for spatial frequency, spectra and contrast. Importantly, race information was not relevant for task execution. The Stop Signal Delay (SSD) was adjusted dynamically for each face category (AA,EA,WC) with the standard adaptive tracking-procedure. Inhibition efficiency was investigated for each race: from inhibition functions, i.e. p(response|stop signal) respectively to SSDs fitted through a Weibull function, we extrapolated critical SSD values (0.5 proportion of inhibitory failures). Moreover, the Stop Signal Reaction Time (SSRT, measure of inhibitory latency) was also measured. Additionally, an Implicit Association Task (IAT) was conducted for each face race to assess both implicit racial attitudes with positive/negative semantics and the speed of face categorization by race. Our data show that WC observers reported better inhibition efficiency for AA faces compared to EA and WC. Additionally, from the IAT we found higher associations with negative semantics for AA compared to both WC and EA faces, as well as the other-race face categorization advantage. However, these two measures did not correlate with action inhibition efficiency. Our data show that other-race faces cannot be considered as a visual and homogeneous social category. The present finding offers new insights and future directions on the many interactions between the visual and social processes related to the visual early extraction of race from faces.