Collective Behavior and Why Some Crowds Get Out of Control

How do law-abiding people get caught up in dangerous group dynamics? Learn the sociology behind collective behavior and contagion theory.

By Alisa Bowman
Mar 6, 2023 2:00 PM
Crowd behavior
A crowd walking and depicting crowd mentality. (Credit: blvdone/Shutterstock)


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In the months after the Jan. 6 riot in Washington, D.C. in 2021, several defendants claimed that their crimes weren’t their fault. According to their defense teams: The crowd made them do it.

At least for some of them, the defensive strategy failed to deliver, and they were found guilty on multiple charges. That said, it all begs the question: Can crowds really make people behave in ways that are deeply at odds with their values? If so, are any of us immune to collective behavior?

Contagion Theory

Back in the late 1800s, French scholar Gustave Le Bon argued that, when in a large crowd, individuals can lose their ability to think rationally. The crowd, he wrote, serves as a hypnotic influence that triggers otherwise rational people to become violent.

Known as “contagion theory,” Le Bon’s reasoning was used as a defensive strategy in 1993, to explain why two men beat a truck driver during the 1992 Los Angeles riots. That time, it partially worked, since the men escaped the most severe charges. But when it was used again after Jan. 6, it saw less success.

Read More: Why Are Emotions Contagious?

The Science of Crowd Behavior

Thing is, the premise has never been scientifically tested, and has fallen from favor among social psychologists.

“Crowds can have an effect on individual behavior, but I don’t think anyone in social psychology would argue that we’re therefore not responsible for our actions,” says Jared B. Kenworthy, a professor of social psychology at the University of Texas at Arlington.

Collective Behavior Examples

Whether or not someone takes part in large-group illegal behavior depends on whether they share an identity with the people around them. A lone Philadelphia Eagles fan might refuse to join up with a group of Kansas City Chiefs fans who are tearing down the goalposts. That person might even get judge-y, thinking, “I can’t believe they’re doing that!”

The same Eagles fan, however, might feel inclined to hurl full cups of beer toward the Chief’s mascot, KC Wolf, assuming other Eagles fans are doing the same.

“If you are in a group of people that you identify with, then whatever they are doing is almost by definition acceptable and you’ll be susceptible to that,” says Kenworthy. “The pre-existing condition is that you have to identify with this group of people.”

These shared identities can involve any point of common interest, including political beliefs, national identity, ethnicity and race, and, yes, your chosen sports team.

Read More: The Psychology Behind Cults

Getting Caught v. the Reward

Most people wouldn’t throw a brick through a storefront, race inside, grab as many items as they can and then sprint back out. In part, they know there’s a high likelihood of getting caught.

However, let’s say someone else has already tossed a brick through the storefront window and there are already dozens of people inside, grabbing as much as they can carry. Now, it feels like someone else is responsible for the crime. On top of that, you might feel like an anonymous face in the crowd, which lowers your perceived risk of getting caught, says Tamara D. Herold, associate professor of criminal justice at the University of Nevada, Las Vegas.

If the crowd cheers you on, the illegal behavior may feel thrilling, says Herold.

“It’s not that we lose our mind,” says Herold. “It’s not that we lose our ability to reason. It’s not that we lose who we are in terms of our core essence. It’s that we’re influenced by our environment.”

The Sociology of Collective Behavior

As we watch rowdy crowd behavior unfold on our television sets, many of us smugly think something like, “I would never. What’s wrong with those folks?”

But that may be pure hubris.

“If there’s one pretty predictable lesson that comes out of social psychology, it’s that we are poor predictors of our own behavior,” says Kenworthy.

If you asked people before a rowdy event how they would behave, most would probably tell you that they would never harm someone or destroy property — because they know those things are considered socially undesirable.

“But when we are actually in the situation it becomes a different story,” Kenworthy says.

How to Crowd-Proof Your Behavior

Assuming an arrest isn’t something you want to see in your future, consider the following before heading to a crowded event.

  • Know your weaknesses. Think about your past behavior when part of a group, suggests Carolina Estevez, a clinical psychologist with Infinite Recovery. Have there been times when you’ve acted impulsively or let yourself be influenced by others around you? Use that information to develop strategies for avoiding those pitfalls in the future, she says.

  • Think about your values. Know what behavioral lines you won’t cross, no matter the circumstances. If you’re willing to cross some lines depending on the circumstances — for example, you might tackle someone to stop them from harming someone else — know what those circumstances are ahead of time.

  • Have an exit plan. Think about the situations that might arise during an event and come up with a plan for dealing with them, suggests Kenworthy. What will you do if the crowd attacks bystanders? Steals things? Destroys property? Panics and runs, trampling anyone in their path? How would you separate yourself from that behavior?

  • Connect with the crowd during the calm. By chatting about other common interests ahead of time, you’ll form bonds. “That way if you need to ask for help to facilitate calm and safety, the crowd becomes a force multiplier,” says Herold. 

Read More: Shame and the Rise of the Social Media Outrage Machine

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