Our lives are spent participating in social interactions. However, the neurophysiological mechanisms supporting the uniquely human drive to cooperate are still largely unknown. Why do humans make efforts to act together instead of alone? What motivational drive sustains these efforts throughout the… Read more interaction? The present project originates in the intuition that the socio-cognitive building blocks of human cooperation and its underlying motives could be unveiled by studying minimally collaborative motor interactions in which agents need to exchange information non-verbally to achieve a goal together. Such information exchange is allowed by sensorimotor communication (SMC), that is, the ability to carve the kinematics of instrumental movements (like those implied in passing over an object) to communicate specific information to the receiver (e.g., “be careful, it is heavy”) without turning to speech. I hypothesize that SMC constitutes a perfect test case to study the neurophysiological mechanisms underlying our motivation to cooperate. Indeed, the kinematic deviations from standard action execution required by SMC implementation are costly (i.e., they imply an effort). What drives and sustains this effort? In three separate work packages, I will test three intertwined hypotheses: (i) we incur the costs required by SMC implementation because SMC fosters action prediction in the receiver and interaction efficiency; (ii) when the receiver follows SMC cues, reward signals arise in the sender; thus, the use of SMC is reinforced by dopamine-mediated learning; (iii) this rewarding flavor of SMC-mediated interactions promotes affiliation. These hypotheses will be explored by applying a novel interactive task (the “core” SMC experiment) to real and virtual interactions in healthy participants, child-caregiver dyads, and neurological patients. At the neurophysiological level, the role of brain regions involved in action prediction and dopaminergic-mediated learning will be probed in non-invasive brain stimulation and fMRI studies. Altogether, the project will provide evidence for the roots of the intrinsically rewarding nature of motor interactions and open new avenues to future research using SMC as a tool for studying social dysfunction along development and in pathological populations.