Decoding social knowledge in the human brain

The present functional MRI study addressed how the brain maps different aspects of social information. We focused on two key dimensions of social knowledge: affect and likableness. Thirty participants were presented with audio definitions, half referring to affective (e.g. \textit{empathetic}) and half to non-affective concepts (e.g. \textit{intelligent}). Orthogonally, half of the concepts were highly likable (e.g. \textit{sincere}) and half were socially undesirable (e.g. \textit{liar}). We used a support vector machine to delineate how both concept dimensions are represented in a set of 9 \textit{a priori} brain regions defined from previous meta-analyses on semantic and social cognition. We show that average decoding in semantic regions (e.g. lateral temporal lobe, inferior frontal gyrus, and precuneus) outperformed social ROIs (e.g. insula and anterior cingulate), with the lateral temporal lobe containing the highest amount of information about the affect and likableness of social concepts. We also found that the insula had a bias towards affect while the likableness dimension was better represented in anterior cingulate cortex. Our results do not support a modular view of social knowledge representation. They rather indicate that the brain representation of social concepts implicates a distributed network of regions that involves ‘domain-specific’ social cognitive systems, but with a greater dependence on language-semantic processing.