Interpersonal synchrony, the temporal coordination of actions between individuals, is fundamental to social behaviors from conversational speech to dance and music-making. Animal models indicate constraints on synchrony that arise from endogenous rhythms: Intrinsic periodic behaviors or processes that continue in the absence of change in external stimulus conditions. We report evidence for a direct causal link between endogenous rhythms and interpersonal synchrony in a music performance task, which places high demands on temporal coordination. We first establish that endogenous rhythms, measured by spontaneous rates of individual performance, are stable within individuals across stimulus materials, limb movements, and time points. We then test a causal link between endogenous rhythms and interpersonal synchrony by pairing each musician with a partner who is either matched or mismatched in spontaneous rate and by measuring their joint behavior up to 1 year later. Partners performed melodies together, using either the same or different hands. Partners who were matched for spontaneous rate showed greater interpersonal synchrony in joint performance than mismatched partners, regardless of hand used. Endogenous rhythms offer potential to predict optimal group membership in joint behaviors that require temporal coordination.

Interpersonal synchrony, the temporal coordination of actions between individuals, is fundamental to social behaviors from conversational speech and dance to music-making. Interpersonal synchrony is associated with affiliation and rapport between partners (Cacioppo et al., 2014; Kirschner & Tomasello, 2010), suggesting it may facilitate group cohesion. What factors facilitate—and constrain—interpersonal synchrony? Evolutionary biology provides some clues: A few nonhuman animal species are able to coordinate the timing of their behavior with external rhythms that match their endogenous (spontaneous) rates of movement (Cook, Rouse, Wilson, & Reichmuth, 2013; Hasegawa, Okanoya, Hasegawa, & Seki, 2011; Patel, Iversen, Bregman, & Schulz, 2009). Humans are capable of synchronizing their behavior with a broader range of external rhythms than are other species. We address here whether humans’ ability to synchronize with others is similarly influenced by endogenous rhythms.

Endogenous rhythms in biology refer to periodic behaviors...