This project aims to define a coherent model of motor interactions, a crucial aspect of social life. So far, there is no consensus on the underlying cognitive and neural mechanisms beyond those associated with imitative behaviors. We are testing the hypothesis that motor interactions are based on the ability to integrate one’s own and a partner’s action within a unitary, dual-person (dyadic), motor plan. With a novel “minimally-joint” paradigm we are testing this hypothesis behaviorally, and we are using fMRI to describe the underlying neurophysiological patterns. This will allow us to provide a theoretical model of motor interactions with potential implications for the rehabilitation of motor deficits.