The emergence of pro-social behaviors and social interacton skills is a major focus of research on children’s development. Here, we consider one important feature of human social interactons, interpersonal movement synchrony, and explore its efects on pro-sociality among young children. Coordinated movements are a crucial part of mother–infant interactons, with important social efects extending well into childhood. Musical interactons are also known to facilitate bonding between infants and caretakers and pro-sociality among peers. We specifcally examine the pro-social effects of interpersonal movement synchrony in a naturalistc peer-play context among 4- to 6-year-old children. We assessed the amount of helping behavior between pairs of children following an actvity that they performed synchronously or nonsynchronously. Children who engaged in synchronous play, as compared with nonsynchronous play, showed signifcantly more subsequent spontaneous helping behavior. Further, more mutual smiling and eye contact were observed in the synchronous conditon and amounts of mutual smiling and eye contact during the movement task correlated with amount of helping behavior observed. Neither measure mediated the conditon-wise efects on helping, however. These results are discussed in terms of their contributon to existng literature and their broader implicatons for the development of pro-sociality and coordinated movements in early childhood.
