“… 22 , 23 , 24 For example, while playing music, musicians exhibit ancillary movements (e.g., body sway and head nodding) that are not strictly essential for the musical output but might help co-performers to synchronize 25 , 26 , 27 or a student to learn new musical material. 24 , 28 Similarly, addressees in a conversation spontaneously produce long eye blinks that can be read as a signal regulating turn-taking behavior. 23 , 29 Notably, as compared to instructed movements, spontaneously produced movements rely on distinct cognitive and neurobiological resources 22 , 30 , 31 , 32 , 33 , 34 and therefore their interpersonal synchronization should not be taken for granted.…”