Increased sensitivity to social hierarchy during social competition versus cooperation.

Social hierarchy is a typical feature of social organization. The ability to quickly recognize social hierarchy information is crucial for adapting to social contexts. Here, we adopted fast periodic visual stimulation with electroencephalography to assess the neural responses to social hierarchy during social competition and cooperation, respectively. Participants first learned hierarchical faces from a competitive game versus a cooperative game. We then sequentially presented the learned hierarchical faces with a specific frequency in a set of faces. Results showed that participants rated the inferior player as lower in the social hierarchy in the cooperative context compared to the competitive context, indicating that social context affects the judgment of others' rank. Moreover, higher neural responses to high and low-hierarchy faces versus medium-hierarchy faces were observed, suggesting rapid discrimination of social hierarchy from faces. Interestingly, rank-specific neural responses were more pronounced in the competitive context than in the cooperative context, indicating increased sensitivity to social hierarchy during social competition versus social cooperation. This study provides behavioral and neural evidence for rapid, automatic processing of social hierarchy information and for an increased sensitivity to such information in competitive versus cooperative social contexts.