Teams tend to do things together. Soldiers march in step. Athletic teams do stretches and simple drills together as a unit. In public schools, all students repeat phrases together like the Pledge of Allegiance. At stadiums, fans will chant together and make similar movements.

There is quite a bit of work that suggests acting in synchrony like this can increase people’s sense of teamwork and conformity. Why does that happen? What happens to people watching others acting together?

Those questions were addressed in a paper by Ping Dong, Xianchi Dai, and Robert Wyer in the January 2015 issue of the Journal of Personality and Social Psychology.

In one study, they had a group of participants learn a set of four basic physical exercises. Some groups performed the exercises all together as they counted off. Other groups performed the exercises at their own pace, so that everyone was doing something different. In addition to these actors, there were also observers. Some participants watched the exercise being done. They watched either a group moving in synchrony or a group in which there was no synchrony. After observing, actors rated how free they felt, and observers rated how free the actors were.

As a measure of , after performing or observing the exercise, participants read reviews about products from a number of different categories (like sofas). The reviews included information about how popular a particular brand was. After reading descriptions of three products for each category, participants chose one. The measure of conformity was the overall popularity of the products participants chose. The more popular the brands, the more that these participants were conforming with others.

In this initial study, participants who performed the exercises with others in synchrony tended to select more popular products than those who performed the exercises without synchronizing their movements with others. Interestingly, the observers showed the opposite pattern. They were more likely to select popular products when they observed groups who moved at their own pace rather than those who acted together in synchrony.

Why did this happen? The observers rated that the actors were significantly less free when they acted in synchrony with others than when they did what they wanted to. Interestingly, the actors who performed the exercises did not differ in how free they felt regardless of whether they were instructed to act in synchrony.

This suggests that actors feel a common bond with people when they act in synchrony. The shared goal and the shared movement create a sense of wanting to agree with the actions of others. In contrast, the observers focused on the individual freedom of the people. When they watched people moving together, they were concerned about freedom, and so they resisted picking products that other people liked.

In several other studies, the researchers expanded on this point. In one study, for example, the actors who were told to move in synchrony were told that they were part of a in which they would win a prize if their team moved together most effectively. The group of actors who moved independently was not given these instructions. The observers were told that they were judging the synchrony of the team they were watching for a competition. Some of the observers were told that if their team won, they would share in the winnings, so that the observer became part of the common goal of the team.

Finally, at the end of the study, participants were given an opportunity to donate money to one of six charities. Three of the charities were well known, and the rest were not well known. The amount of money given to well-known charities was the measure of conformity in this study.

Overall, actors who moved in synchrony tended to give more money to well-known charities than the observers who watched them. However, when the observer was also made to feel part of the team, the observer gave more money to well-known charities than to unpopular charities. As in the previous study, actors who did not move in synchrony did not have a to conform: They gave about the same amount of money to popular and unpopular charities.

Putting these findings together, when a group moves in synchrony, it increases people's sense of belonging to a group and increases the willingness of members of that group to conform with others. Observers have a different experience. Watching others move in synchrony makes observers sensitive to the loss of freedom of those moving together. Those observers are actually less wiling to conform as a result of watching the movements.

In this way, synchronous movements are a double-edged sword. They increase a sense of belonging in those who are made to feel part of the team, but they actually decrease that sense of belonging to those who see themselves as outsiders.

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