Social Decision Preferences for Close Others are Embedded in Neural and Linguistic Representations

Humans frequently make decisions that impact close others. Prior research has shown that people have stable preferences regarding such decisions and maintain rich, nuanced mental representations of their close social partners. Yet, if and how such mental representations shape social decisions preferences remains to be seen. Using a combination of functional magnetic resonance imaging (fMRI) and natural language processing (NLP), this study investigated how neural and linguistic representations of close others influence social decision-making. Participants nominated a parent and a friend, rated their characteristics, and made hypothetical social decisions while undergoing fMRI. Neural representations of parents and friends, relative to the self, predicted social decision preferences. Specifically, greater neural similarity between self and parent in the temporoparietal junction (TPJ) and nucleus accumbens (NAcc) was associated with a preference for parents, while greater self-friend similarity in the medial prefrontal cortex (mPFC) predicted friend-preference. Additionally, linguistic analysis of written descriptions of close others revealed that social decision preferences could be reliably predicted from semantic features of the text. The convergence of neural and linguistic data further strengthened the prediction of social decision preferences. These findings elucidate the neural and linguistic underpinnings of social decision-making, emphasizing the critical role of mental representations in guiding choices involving familiar others.