The good, the bad, and the in-between: an exploratory study of how different groups may be represented in the brain.

Introduction: Social categorization is a fundamental aspect of social perception, enabling individuals to process vast amounts of information efficiently. This exploratory fMRI study investigated whether different types of social groups are represented in the brain as stable memory representations. Methods: We used repetition suppression as a proxy-measurement for such stable representation, examining four groups categorized by their warmth and competence into the quadrants of the Stereotype Content Model (SCM). Participants judged the typicality of behavioral sentences associated with these groups, presented in pairs that either repeated the same group, or not. Results: A repetition suppression pattern was observed in the posterior temporal sulcus (pSTS) for groups with mixed warmth and competence; specifically the rich (low warmth, high competence) and the poor (high warmth, low competence). By contrast, no suppression was detected for non-mixed groups (military people and welfare recipients). Discussion: We theorize that mixed groups elicit greater ambiguity, which may prompt the brain to form more robust representations to quickly assess their functional relevance. These findings suggest that stable group representations are not uniformly applied across all group types and may reflect social complexity and motivational salience. The results highlight the pSTS as a key node in group representation and invite further research into its functional role.