Neural systems for processing social relationship information along two principal dimensions.

Comprehending the social relationships of others is essential for daily social interactions. Previous research has revealed the neural substrates involved in inferring others' mental states and detecting social features. However, the neural bases underlying the processing of complex information about diverse human social relationships remain poorly understood. Here, using empirical data collected while participants viewed naturalistic movie clips and evaluated social relationships inside an fMRI scanner, we identify two primary dimensions underlying social relationship recognition. The first dimension reflects Amity-Hostility, while the second dimension encompasses Restrained Amity-Suppressive Hostility. Moreover, the first dimension is predominantly processed within a posterior cortical network centered around the posterior superior temporal sulcus (pSTS), while the second dimension is primarily processed within an anterior cortical network centered around the ventromedial prefrontal cortex (vmPFC). These findings suggest a framework for understanding the neural bases of human social recognition, emphasizing information-based processing along two principal dimensions, each engaging distinct neural systems in the brain.