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

From a young age, children have advanced social perceptual and reasoning abilities. However, the neural development of these abilities is still poorly understood due to the challenges of acquiring brain imaging data from young children with traditional neuroimaging methods. To address this gap, we used 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 labeled the movie with visual and social features, including motion energy, presence of a face, presence of a social interaction, theory of mind (ToM) events, valence and arousal. Using a voxel-wise encoding model trained on these features, we find that models based on 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, models based on individual social features 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 in a natural movie and suggests social interaction perception is supported by early developing neural responses in the STS.