The Science Behind Why People Follow the Crowd

Why do other people influence us so much?

Posted May 24, 2017

Source: Neko1998/Flickr

It may seem that we are in control of our thoughts and behavior. But social psychology tells a different story.

Social psychology is defined as “the scientific study of how we think about, influence, and relate to one another." We are social beings. Most of us communicate with others every day, spending large portions of our waking hours in some form of communication.

One lesson from social psychology is the influence others have on us. Research shows we do not have as much control over our thoughts and behavior as we think. We take cues from our environment, especially other people, on how to act.

How groups influence us

Consider the concept of group polarization. The idea is that likeminded people in a group reinforce one another’s viewpoints. Group polarization strengthens the opinions of each person in the group. 

In a study by French psychologists Serge Moscovici and Marisa Zavalloni, researchers asked participants some questions. First, researchers asked about their opinion of the French president. Second, they asked about their attitude toward Americans. The researchers then asked the participants to discuss each topic as a group.

After a discussion, groups who held a tentative consensus became more extreme in their opinions. For example, participants held slightly favorable attitudes toward the French president. But their attitudes magnified as group members spoke with one another. They held slightly negative attitudes toward Americans. But their attitudes intensified as each member learned others shared their views about their allies abroad. The researchers concluded, “Group consensus seems to induce a change of attitudes in which subjects are likely to adopt more extreme positions." When we see our uncertain opinions reflected back to us, our beliefs strengthen.

Many of us also enjoy being with others who share similar beliefs. In one experiment, researchers invited people to discuss issues including same-sex marriage, affirmative action, and climate change. People in one group came from predominantly liberal Boulder, Colorado. People in another group came from mostly conservative Colorado Springs. The discussions on controversial topics led to increased agreement within the groups. Beliefs we hold are strengthened when we are around others who hold similar views.

If other people do it, that means it’s right. Right?

There is a heuristic most of us use to determine what to do, think, say, and buy: the principle of social proof. To learn what is correct, we look at what other people are doing. In his bestselling book Influence: The Psychology of Persuasion, psychologist Robert Cialdini writes, “Whether the question is what to do with an empty popcorn box in a movie theater, how fast to drive on a certain stretch of highway, or how to eat the chicken at a dinner party, the actions of those around us will be important in defining the answer.” Social proof is a shortcut to decide how to act.

Cialdini has used the principle of social proof to prevent environmental theft. Consider the case of Arizona’s Petrified Forest National Park. Visitors would arrive at the park and learn of past thievery from prominent signs: “Your heritage is being vandalized every day by theft losses of petrified wood of 14 tons a year, mostly a small piece at a time.”

In one experiment, Cialdini removed the sign from a specific path in the park to measure any differences it might make. The path with no sign had one-third less theft than the path with the sign. Visitors interpreted the sign’s message as permission. Put differently, visitors thought it was “normal” to take small pieces of wood, because so much was stolen every year.

Researchers have also used the principle of social proof to help people overcome their fears. In one study, Albert Bandura and his colleagues worked with a group of young children frightened of dogs. The children watched a four-year-old boy happily play with a dog for 20 minutes a day for four days. After the four day period, 67 percent of the children who watched the boy play with the dog were willing to enter a playpen with a dog. When the researchers conducted a follow-up study one month later, they found the same children were willing to play with a dog.  Watching a little boy have fun with a dog reduced fear in children. They used the behavior of a boy playing with a dog as a model to change their own behavior.

Why do others influence us so much?

Clearly, others affect our behavior. One reason for this is that we live in a complex world. We use the decisions of others as a heuristic, or mental shortcut, to navigate our lives. English philosopher and mathematician Alfred North Whitehead once said, “Civilization advances by extending the number of operations we can perform without thinking about them."

In his book Influence, Cialdini uses the example of advertisers informing us that a product is the “fastest-growing” or “best-selling.” Advertisers don’t have to persuade us that a product is good, they only need to say others think so

Cialdini notes that consumers often use a simple heuristic: Popular is good. Following the crowd allows us to function in a complicated environment. Most of us do not have time to increase our knowledge of all merchandise and research every advertised item to measure its usefulness.


A second reason others influence us is that humans are social. We have survived because of our ability to band together. Early humans who formed groups were more likely to survive. This affected our psychology.

As Julia Coultas, a researcher at the University of Essex, puts it, “For an individual joining a group, copying the behaviour of the majority would then be a sensible, adaptive behaviour. A conformist tendency would facilitate acceptance into the group and would probably lead to survival if it involved the decision, for instance, to choose between a nutritious or poisonous food, based on copying the behaviour of the majority.” 

In our evolutionary past, our ancestors were under constant threat. Keen awareness of others helped our ancestors survive in a dangerous and uncertain world. Modern humans have inherited such adaptive behaviors.

These behaviors include banding together and promoting social harmony. This includes not dissenting from the group. In a hunter-gatherer group, being ostracized or banished could have been a death sentence.

Thoughtful reflection on social influence may lead us to a greater awareness of ourselves and our relationships with others.


Bandura, A., Grusec, J. E., & Menlove, F. L. (1967). Vicarious Extinction of Avoidance Behavior. Journal Of Personality And Social Psychology, 5(1), 16-23. doi:10.1037/h0024182


Cialdini, R. (2007). Influence: The psychology of persuasion (Rev. ed. ; 1st Collins business essentials ed.). New York: Collins.

Coultas, J. C. (2004). When in Rome .... An Evolutionary Perspective on Conformity. Group Processes & Intergroup Relations, 7(4), 317-331. doi:10.1177/1368430204046141

Lee, D., & Hatesohl, D. (n.d.). Listening: Our Most Used Communication Skill. Retrieved September 8, 2014.

Moscovici, S., & Zavalloni, M. (1969). The group as a polarizer of attitudes. Journal Of Personality And Social Psychology, 12(2), 125-135. doi:10.1037/h0027568

Schkade, D., Sunstein, C. R., & Hastie, R. (2007). What Happened on Deliberation Day?. California Law Review, 95(3), 915-940.