Effect of social interaction negative affect on within-person mentalizing network connectivity

Understanding others' intentions and emotions is supported by the mentalizing network, helping people navigate the inherently complex dynamics of social interactions. However, work investigating the mentalizing network often relies on non-naturalistic methods, limiting our understanding of individual differences most apparent within social interaction contexts. We took a naturalistic, multilevel approach to investigate relations between real-world affective expressions, social anxiety symptoms and mentalizing network connectivity. Same gender-identity friend pairs (40 participants; 62.5% Women; 87.5% White) engaged in a social interaction while videos from their individual visual perspectives were recorded. Participants were later scanned while they watched clips of the interaction from their own (self run) and their friend's (friend run) perspective. We found that expressed negative affect, not expressed positive affect, related to within-person variation in mentalizing network connectivity across perspectives. Further, participants higher in social anxiety symptoms showed more consistent mentalizing network connectivity across perspectives when expressed negative affect was higher than average, and particularly when friend negative affect expressions, rather than their own negative affect expressions, were higher. Mentalizing network connectivity may be responsive to shifts in negative affect during social interactions and individuals with higher social anxiety may find negative affect from a friend particularly salient.