Linking Intuitive Physics to Social Cognitive Attributions

Does our perception of physical events and social interactions rely on shared or unique neural mechanisms? Computational modeling of Heider-Simmel style animations suggests that observers represent physical causality and social interactions within a unified psychological space, such that there exists a gradient that links the two perceptual interpretations that is well described by metrics of intentionality and violation of physics (Shu et al. 2021). Studies of brain function, however, have more clearly identified unique regions for social interactions vs intuitions on physical causality. Specifically, the posterior superior temporal sulcus (pSTS) and temporoparietal junction (TPJ) are involved in perceiving the dynamics of social interactions and the implied underlying intentions and beliefs. Here, we seek to evaluate whether neural representations in the pSTS and TPJ can be explained within the framework of the computational model’s unified psychological space. Method. Participants viewed short (approximately 3 sec) Heider-Simmel type animations depicting two objects/agents moving within a room. The dynamics of the objects/agents varied systematically such that they conveyed different degrees of intentionality. In a rapid event-related design, we measured the BOLD response while observers passively viewed the sequences. Results. Multivariate analysis shows activity patterns in the pSTS/TPJ that accurately classify the categorical perception of social vs physical, consistent with previous reports. A representational similarity searchlight analysis reveals neural similarity structure correlated with the computational model in early visual areas and the human MT+ complex/lateral occipital cortex, which likely reflects perceptual features such as velocity and acceleration that give rise to the perception of intentionality. Conclusion. These results are consistent with a representational gradient of physical and social events in perceptual brain regions that cascades to categorical representations within higher social-cognitive brain systems.