Human synchronization in groups occurs when individuals align a sequence of behaviors simultaneously in time with others. Distinct from mimicry or social mirroring behaviors, group synchrony refers to the fine-grained temporal relationships between each group member’s sequence of actions (e.g., the production of musical tones) that show fast adaptation to other group members’ actions. Synchronization arises not only in intentionally coordinated groups such as rowing teams or military parade marchers but also in unintentional situations such as walkers’ gait [1], spectators’ chants [2], or listeners’ body sway in response to music [3,4] or to speech [5].