A Cognitive Neuroscience of Social Groups

Abstract

We used functional magnetic resonance imaging to investigate how the human brain processes information about social groups in three domains. Study 1: Semantic knowledge. Participants were scanned while they answered questions about their knowledge of both social categories and non-social categories like object groups and species of nonhuman animals. Brain regions previously identified in processing semantic information are more robustly engaged by nonsocial semantics than stereotypes. In contrast, stereotypes elicit greater activity in brain regions implicated in social cognition. These results suggest that stereotypes should be considered distinct from other forms of semantic knowledge. Study 2: Theory of mind. Participants were scanned while they answered questions about the mental states and physical attributes of individual people and groups. Regions previously associated with mentalizing about individuals were also robustly responsive to judgments of groups. However, multivariate searchlight analysis revealed that several of these regions showed distinct multivoxel patterns of response to groups and individual people. These findings suggest that perceivers mentalize about groups in a manner qualitatively similar to mentalizing about individual people, but that the brain nevertheless maintains important distinctions between the representations of such entities. Study 3: Social categorization. Participants were scanned while they categorized the sex and race of unfamiliar Black men, Black women, White men, and White women. Multivariate pattern analysis revealed that multivoxel patterns in FFA--but not other face-selective brain regions, other category-selective brain regions, or early visual cortex--differentiated faces by sex and race. Specifically, patterns of voxel-based responses were more similar between individuals of the same sex than between men and women, and between individuals of the same race than between Black and White individuals. These results suggest that FFA represents the sex and race of faces. Together, these three studies contribute to a growing cognitive neuroscience of social groups.