Beyond synchrony: the capacity of fMRI hyperscanning for the study of human social interaction.

Hyperscanning-simultaneous brain scanning of two or more individuals-holds great promise in elucidating the neurobiological underpinnings of social cognitive functions. This article focuses on functional magnetic resonance imaging (fMRI) hyperscanning and identifies promising targets for studying the neuroscience of social interaction with fMRI hyperscanning. Specifically, we present applications of fMRI hyperscanning in the study of social interaction along with promising analysis approaches for fMRI hyperscanning, with its high spatial and low temporal resolution. We first review fMRI hyperscanning studies in social neuroscience and evaluate the premise of using this costly neuroimaging paradigm. Many second-person social neuroscience studies are possible without fMRI hyperscanning. However, certain fundamental aspects of social cognition in real-life social interactions, including different roles of interactors, shared intention emerging through interaction and history of interaction, can be addressed only with hyperscanning. We argue that these fundamental aspects have not often been investigated in fMRI hyperscanning studies. We then discuss the implication of the signal coupling found in fMRI hyperscanning and consider analysis approaches that make fair use of it. With fMRI hyperscanning, we can explore not only synchronous brain activations but whole-brain asymmetric activation patterns with a lagged association between interacting individuals.