Early neural development of social perception: evidence from voxel-wise encoding in young children and adults

From a young age, children show advanced social perceptual and reasoning abilities. However, the neural development of these abilities is still poorly understood. To address this gap, we used publicly available fMRI data collected while children and adults watched an engaging and socially rich movie to investigate how the cortical basis of social processing changes throughout development. We annotated segments of the movie with visual and social features, including motion energy, presence of faces, presence of a social interaction, theory of mind (ToM) events, valence and arousal. Using a voxel-wise encoding model trained using these features, we find that visual (motion energy) and social (faces, social interaction, ToM, valence, and arousal) features can both predict brain activity in children as young as three years old across the cortex, with particularly high predictivity in motion selective MT and the superior temporal sulcus (STS). Furthermore, individual social feature models showed that while representations for some social features, like ToM, develop throughout childhood, social interaction representations in the STS appear adult-like in even the youngest children. The current study, for the first time, links neural activity in children to specific social features during naturalistic movie viewing and suggests social interaction perception is supported by early developing neural responses in the STS.