Behavioral and neural markers of social vision

Research on face perception has revealed highly specialized visual mechanisms such as configural processing, and provided markers of interindividual differences -including disease risks and alterations- in visuoperceptual abilities that traffic in social cognition. Is face perception unique in degree or kind of mechanisms, and in its relevance for social cognition? Combining functional MRI and behavioral methods, we address the processing of an uncharted class of socially relevant stimuli: minimal social scenes involving configurations of two bodies spatially close and face-to-face as if interacting (hereafter, facing dyads). We report category-specific activity for facing (vs. non-facing) two-body configurations in selective areas of the visual cortex. That activity shows face-like signatures of configural processing -i.e., stronger response, and greater susceptibility to stimulus inversion for facing (vs. non-facing) dyads-, and is predicted by performance-based measures of body-dyad perception (i.e., accuracy in a fast visual categorization task). Moreover, individual performance in body-dyad perception is reliable, stable-over-time and correlated with the individual social sensitivity, coarsely captured by the Autism-Spectrum Quotient. Further analyses clarify the relationship between single-body and body-dyad perception. We propose that facing dyads are processed through highly specialized mechanisms (and brain areas), analogously to other biologically/socially relevant stimuli such as faces. Like face perception, facing-dyad perception can reveal basic visual processes that lay the foundations for understanding others, their relationships and interactions. Significance statementWith its specialization to faces and biological motion, vision houses the foundations of human social ability. Using a multimodal approach (meta-analysis, fMRI, visual-perception tasks and self-administered survey), we introduce a new class of visual stimuli -minimal social scenes with two face-to-face bodies-, whose processing highlights new behavioral and neural markers of visuoperceptual abilities that traffic in social cognition. Behavioral and neural effects of body-dyad perception reveal the recruitment of specialized configural processing, previously described for face perception. Furthermore, individual performance in body-dyad perception is stable over time, and predicts an individuals social sensitivity, measured in terms of autism-spectrum traits. Thus, body-dyad perception reveals uncharted aspects of visual functioning and specialization, which may critically contribute to human social life.