You see someone coming toward you from a distance and, though you cannot make out the features of his face, you instantly recognize your friend by his distinctive walk. We all have experienced this moment — after all, everyone has a unique way of walking and moving through the world. A new study explores whether our natural movement, one aspect of our individuality, would shine through even when we mimic someone else.

University of Exeter researchers say they can identify an individual motor signature (IMS) that captures “the subtle differences in the way each of us moves.” Comparing an IMS of one person with that of another would reveal either a natural rapport or lack of one, the research team believes. Ultimately, their new findings support “the theory of similarity, specifically that dynamic similarity of participants’ solo movements enhances their coordination level,” wrote the research team, led by Krasimira Tsaneva-Atanasova, a professor of mathematics.

Psychologists say mimicry is a form of “social glue.” Imitation facilitates friendships, supports group cohesion, and can even expedite cross-cultural learning, suggests a 2011 study. Mirroring, as the behavior is known, is considered a form of nonverbal communication that mostly occurs unconsciously. The two people involved are generally unaware when and how mirroring occurs. For instance, imagine yourself and a friend drinking coffee together and both of you lean forward across the kitchen table at nearly the same moment. In that instant, the mirroring seems natural, part of the general back and forth of conversation, just as the positive feeling this small mimicry evokes also feels genuine to you.

If imitative body language leads to positive feelings, do people who move in similar ways relate to one another more easily? To understand if similar motion leads to compatibility, Tsaneva-Atanasova and her colleagues designed a simple series of experiments.

Individual Motor Signature

The research team, which included mathematics and engineering experts from the University of Bristol, Montpellier University, and the University of Naples Federico II, used a mirror game — where two people face each other and imitate each other’s movements — as the inspiration for their study.

First, they asked participants to create an interesting motion by moving their one hand above a leap motion sensor connected to a laptop, while the researchers recorded the way individuals went about the motion, or their signature movements. In the next experiment, the researchers collected data as participants played the mirror game with a partner, where they tracked each other’s movements. In the final phase of the study, the participants, closely observed by the researchers, attempted to mimic the motions of a virtual player.

Data from the first phase of the study, the researchers say, established the existence of the IMS, with each participant displaying differences in natural movements: some tending toward faster, lighter, or smoother motions. Because characteristic movements “are stable over time and differ significantly between individual players,” the authors wrote, this dynamic signature could be detected even in the more complicated, non-periodic motions the participants performed during the mirror game of the second and third phase of the study. Essentially, then, even when we imitate another person by moving in ways that may be very uncharacteristic for us, our characteristic gestures, echoes of our inherent personality, are noticeable.

In fact, the researchers say the level of coordination possible between two people depends on how similar they are in natural motion, since people who move in the same way react similarly when working together. Our movements, Tsaneva-Atanasova and her colleagues concluded, provide insight into our fundamental personalities.

Source: Słowinski P, Zhai C, Alderisio F, et al. Dynamic similarity promotes interpersonal coordination in joint action. Interface. 2016.