A social interaction field model accurately identifies static and dynamic social groupings.

Identifying whether people are part of a group is essential for humans to understand social interactions in social activities. Previous studies have focused mainly on the perceptual grouping of low-level visual features. However, very little attention has been paid to grouping in social scenes. Here we implemented virtual reality technology to manipulate characteristics of avatars in virtual scenes. We found that closer interpersonal distances, more direct interpersonal angles and more open avatar postures led to a higher probability of a group being judged as interactive. We developed a social interaction field model that describes a front-back asymmetric social interaction field. This model accurately predicts participants' perceptual judgements of social grouping in real static and dynamic social scenes. Our findings indicate that the social interaction field model is an efficient computational framework for analysing social interactions and provides insight into how human observers perceive the interactions of others, enabling the identification of social groups.