Common social behaviors, such as having a conversation, dancing, or playing a team sport, require precise interpersonal coordination of action. One question that emerges in research on interpersonal coordination is to what extent individuals implicitly mimic the spatial characteristics of movements for tasks that emphasize movement timing. To investigate this question, we conducted two experiments using an interpersonal synchronization-continuation tapping paradigm in which pairs of individuals tapped with their index finger on a table in synchrony with an auditory metronome and then continued tapping at the same tempo when the metronome stopped. Pairs of individuals tapped either together with the instruction to maintain synchrony with each other (interpersonal tapping) or tapped alone (solo tapping). Solo tapping conditions either occurred with their tapping partner present in the testing room (Experiment 1) or absent (Experiment 2). We used motion capture to examine both the spatial and temporal aspects of movement dynamics during task performance. In both experiments, participants implicitly mimicked subtle aspects of spatial elements of their partner's movements. The extent of finger extension (tap amplitude) and, in Experiment 1, duration of finger contact with the surface (dwell time) were correlated between tapping partners when they tapped together. In some cases, this spatial mimicry extended to solo tapping conditions, but only during solo tapping conditions that followed the interpersonal tapping task, and, to a lesser degree, when solo tapping after having observed the other participant solo tapping.
Keywords: Finger tapping; Interpersonal synchronization; Mimicry; Motion tracking; Movement timing.