Law enforcement officers during a protest in Ferguson, Mo., on Aug. 18, 2014. (Michael B. Thomas/AFP/Getty Images)

From civil rights protests to the Rodney King riots to the Battle for Seattle, police facing down large numbers of people often look the same: Stiff-jawed men wearing riot gear marching in synchronized lockstep. It’s apparently the textbook strategy both for self-defense and for crowd control.

But a new study suggests that it may also be a recipe for excessive force and police violence. What researchers call “synchrony” may give authorities a sense of power that encourages them to be more aggressive, the study suggests.

“We have found that when men are walking in step with other men, they think that a potential foe is smaller and less physically formidable and less intimidating than when they’re just walking in no particularly coordinated manner with other men,” lead author Daniel Fessler, a professor of anthropology at the University of California at Los Angeles, said in a university press release. “That calculation appears to make men who march with other men feel less vulnerable and more powerful and their potential foe more easily vanquished. We theorize that it also makes them more likely to use violence than they otherwise would be.”

Police wait to advance after tear gas was used to disperse a crowd on Aug. 17, 2014, during a protest for Michael Brown in Ferguson, Mo. (AP Photo/Charlie Riedel)

“Synchrony is a signal — individuals saying, ‘We got this, we can do this,'” Fessler told The Washington Post in a phone interview.

Fessler and co-author Colin Holbrook published their theory in Biology Letters, a scholarly journal published by the British Royal Society, in a paper entitled: “Marching into battle: synchronized walking diminishes the conceptualized formidability of an antagonist in men.”

The paper does not suggest an alternative approach for authorities confronting large masses of protesters, who also tend to be more whipped up and aggressive in a pack than they would be on their own.

To study synchrony, Fessler recruited 96 male UCLA undergrads. Half walked with a researcher across campus in lockstep — the other half walked at their natural speed.

After their march, participants were shown a “‘mugshot’ of an angry male face,” as the study put it. The result: “Men who walked synchronously with another man envisioned a purported criminal as less physically imposing than did men who engaged in the same task without synchronization.” Put another way: “Synchrony diminished the perceived relative fighting capacity of the foe.”

In layman’s terms: Compared with us guys, you guys don’t look so tough.

University of California Davis Police Lt. John Pike uses pepper spray to move Occupy UC Davis protesters while blocking their exit from the school’s quad in November 2011 in Davis, Calif. (Wayne Tilcock/The Enterprise via AP)

Fessler, an evolutionary anthropologist, said forceful police response to an immigration march in Los Angeles in 2007 and use of pepper spray at the University of California at Davis in 2011 got him thinking about “the dark side to cooperation.” This dark side isn’t just evident in police harassing protesters, but in how, for example, coyotes on the east side of a California mountain ridge will howl all night long at coyotes on the west side.

“The coyotes are saying, ‘We’re bad-ass,'” Fessler said. “‘There are a lot of us and we can move together. You better stay out of our territory.'”

Pumped up by collective action, coyotes — or protesters or police — can be pushed closer to violence, even if violence doesn’t break out. One geopolitical example: North Korea’s ubiquitous goose-stepping.

“They are goose-stepping for no strategic reason,” Fessler said. “Nobody marches into battle anymore. But they are quite literally broadcasting the signal using the airwaves.”

Such a show of force was on display earlier this month in Ferguson, Mo., where police weren’t shy about using heavy hardware against protesters — or, at least, the alleged “agitators” in their midst. As Missouri Highway Patrol Capt. Ron Johnson and U.S. Attorney General Eric H. Holder Jr. tried to defuse tension, those speaking out about the death of Michael Brown faced tear gas, armored vehicles and smoke.

Fessler emphasized that he’s not an expert in police training and that his research was designed long before Brown’s death. Nor does the study say how police should better control crowds.

However, citing Ferguson, he said the militarization of urban police may have negative consequences. Civilians may pay the price if cops, high on fellow-feeling, are too eager to crack skulls.

Los Angeles Police Metro Division officers advace on a crowd during an immigration rally in MacArthur Park in Los Angeles on May 1, 2007. (Photos by Chad K. Uyeno/AP)

“The military mission is an ‘us vs. them’ mission,” Kessler said. “But that’s not the mission of civilian police forces. The motto is ‘protect and serve.’ … When we train them the way we train soldiers, we run the risk that we’re eliciting an ‘us vs. them’ psychology.”

His advice: “Military-style training for an average cop on the beat should not be employed,” he said.

h/t Science Daily