Seeing "us vs. them": Minimal group effects on the neural encoding of faces

Faces are inherently social, but the extent to which social group information affects early face processing remains unknown. To address this issue, we examined cortical activity associated with structural encoding of novel ingroup vs. outgroup faces. Participants were assigned to one of two arbitrarily-defined groups using the minimal group procedure, and event-related potentials (ERPs) were recorded while participants categorized faces of people identified as members of their novel ingroup vs. outgroup. Our analysis focused on the N170 component of the ERP, which peaks 170. ms following face onset and reflects face structural encoding. Ingroup faces elicited larger N170 amplitudes than outgroup faces, suggesting that mere group information affects this initial stage of face perception. These findings show that social categories influence how we "see" faces, thus providing insight into the process through which categorizations may lead to biased intergroup perceptions.