Dynamic similarity promotes interpersonal coordination in joint-action

TL;DR

This paper introduces an individual motor signature (IMS) to quantify personal movement variability, demonstrating that dynamic similarity between individuals enhances coordination in joint actions, supported by experiments with human and virtual avatar interactions.

Contribution

It presents a novel IMS index for individual movement, establishes its invariance and uniqueness, and links dynamic similarity to improved interpersonal coordination.

Findings

IMS is time-invariant and individual-specific.

Higher dynamic similarity correlates with better coordination.

Virtual avatar experiments confirm the role of kinematic features in coordination.

Abstract

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. Furthermore, we use a virtual avatar driven by an interactive cognitive architecture based on feedback control theory to explore the effects of different kinematic features of the avatar motion on the coordination with human players.