Metronomes, cells, neurons, fireflies, and human beings all fall into synchrony with each other, given the opportunity. Synchrony between people appears to generate social cohesion by increasing liking and feelings of togetherness. But the function of dancing, chanting and singing is not just to produce warm, affiliative feelings, anthropologists have speculated, but also to improve group action. The group that chants and dances together hunts well together. Direct evidence for this is sparse, as research so far has mainly focused on studies of pairs, the effects of bodily movement, and measured cooperation and affiliative decisions. In contrast, in our experiment, large groups of people were studied, the synchrony of their verbal behaviour alone was manipulated, and in addition to affiliation, we measured their performance on a memory task and on a group action task, playing a video game together. Our evidence suggests that the effects of synchrony are stable across modalities, and can be generalized to larger groups

When people move together, as they dance, march or flirt, itincreases affiliation between them. But what about ‘movingtogether’ produces affiliation: the movements themselves, orthe social context of moving ‘together’? We instructed pairs ofparticipants to listen to music and move their arms or legsaccording to shapes appearing on screen. They either carriedout the same movements, or when one moved their arms theother moved their legs. They either saw shapes on one laptop,or each had their own laptop. Surprisingly, participants did notlike each other more if they carried out the same movements,but affiliation did increase if they danced looking at the samescreen. Rather than their movements, instructions, intentionsor perceptual experiences, here it is the social context of theactions that produces affiliation, a surprising finding that is noteasily accounted for by the dominant theories of mimicry andbehavioural synchrony.