Human movement has been studied for decades, and dynamic laws of motion that are common to all humans have been derived. Yet, every individual moves differently from everyone else (faster/slower, harder/smoother, etc.).
We propose here an index of such variability, namely an individual motor signature (IMS) able to capture the subtle differences in the way each of us moves. We show that the IMS of a person is time-invariant and that it significantly differs from those of other individuals. This allows us to quantify the dynamic similarity, a measure of rapport between dynamics of different individuals’ movements, and demonstrate that it facilitates coordination during interaction. We use our measure to confirm a key prediction of the theory of similarity that coordination between two individuals performing a joint-action task is higher if their motions share similar dynamic features.
…studies of interpersonal interaction show that people prefer to interact with others who are similar to themselves. Moreover, it has been shown that social movement coordination between interacting people could be used to assess and enhance their mutual rapport. These observations have led to the development of a theory of similarity which predicts that the level of synchronization in joint actions is enhanced if the participants are similar in terms of morphology and movement dynamics and are willing to match their behaviours. Despite previous attempts in the literature, the theory of similarity has not been tested in controlled experiments. In this paper, we demonstrate existence of a time-invariant individual motor signature (IMS), and show how it can be used to study sociomotor coordination.