Sharing a bimanual task between two: evidence of temporal alignment in interpersonal coordination

In recent years, researchers have made many new discoveries in the field of social interaction and have attempted to understand the mechanisms of interpersonal coordination. This research is marked by two streams: On the one hand, there are attempts to explain spontaneous, incidental interpersonal coordination in terms of the behavioral dynamics perspective, and on the other, to explain instructed, intentional interpersonal coordination in terms of joint action. Other paradigms fall somewhere between incidental and intentional coordination, e.g. task sharing paradigms. The present study has two major objectives. First, we wanted to explore to what extent a dyadic scenario for bimanual coordination mimics typical signatures of bimanual coordination performance as obtained in the classical individual scenario. Second, if such mimicking is obtained, we wanted to investigate the kind of information on which the coordination between the two individuals may be grounded. To do so, we used a bimanual aiming task, which enabled us to assess measurements of two levels of coordination: global (operating over longer periods of time) and local (operating on each particular trial). In Experiment 1, this task was performed in an individual and in a dyadic setting. In the dyadic scenario, we observed strong global coordination and weak local coordination. In Experiment 2, we replicated this pattern and showed that different kinds of feedback had no impact on interpersonal coordination. Based on these findings, we propose that interpersonal coordination in a non-rhythmic choice response task is based on weak interpersonal coordination.