The Neural Signature of Social Dominance Discrimination by Means of Fast Periodic Visual Stimulation.

Hierarchy is a pervasive feature of social organization. The ability to rapidly discriminate hierarchical information is critical for social interaction. Here, we took advantage of a special technique in electroencephalography (EEG) known as fast periodic visual stimulation (FPVS). We used this technique, which captures the automatic perception of faces, to explore the neural signature of social dominance discrimination. A stream of computer-generated faces was presented at 6 Hz, i.e. six faces/second. In the experimental condition, faces alternated from high to low social dominance within a sequence, bringing about a frequency of interest of 3 Hz (6 Hz/2), i.e. three high/low dominance faces appeared in one second. In two control conditions, we presented faces which came exclusively from one of two hierarchical ranks (either lower or higher). Participants were asked to respond to information unrelated to this hierarchical information, namely pressing the spacebar when the fixation changes color. Results revealed a significant 3 Hz response for the experimental condition only. This response was located bilaterally in the occipito-temporal region, indicating discrimination of differences in social dominance. Through the use of FPVS, we provide electrophysiological evidence to show that social hierarchical information can be detected automatically.