What Is Deindividuation in Psychology? Definition and Examples

Why people act differently when they're part of a group

A drawing of silhouettes of people forming a crowd, on a beige background.

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Why do people seem to behave differently when they're part of a crowd? According to psychologists, one reason is that people can experience a state known as deindividuation.

This article looks at the definition of deindividuation, how it affects behavior, and what can be done to reduce it—that is, to individuate people.

Key Takeaways: Deindividuation

  • Psychologists use the term deindividuation to refer to a state in which people act differently than they normally would because they are part of a group.
  • Earlier researchers focused on the ways in which deindividuation can cause people to behave in impulsive or antisocial ways, while later researchers have focused on how deindividuation causes people to act in accordance with a group's norms.
  • While certain factors—such as anonymity and a lowered sense of responsibility—can promote deindividuation, increasing self-awareness can serve to promote individuation.

Definition and Historical Background

Deindividuation is the idea that, when in groups, people act differently than they would as individuals. Because of the anonymity that groups provide, psychologists have found that people can even act in impulsive or antisocial ways when they're part of a crowd.

In 1895, Gustave LeBon put forward the idea that being part of a crowd can change people's behavior. According to LeBon, when people join a crowd, their behavior is no longer restricted by the usual social controls, and impulsive or even violent behavior can result.

The term deindividuation was first used by psychologist Leon Festinger and his colleagues in a 1952 paper. Festinger suggested that, when in deindividuated groups, the internal controls that typically guide people's behavior begin to loosen. Additionally, he suggested that people tend to like deindividuated groups, and will rate them more highly than groups with less deindividuation.

Philip Zimbardo's Approach to Deindividuation

But what exactly causes deindividuation to occur? According to psychologist Philip Zimbardo, several factors can make deindividuation more likely to occur:

  • Anonymity: When people are anonymous, their individual behavior can't be judged—which makes deindividuated behaviors more likely.
  • Lowered sense of responsibility: Deindividuation is more likely when people feel that other people are also responsible in a situation, or when someone else (such as a group leader) has taken responsibility.
  • Being focused on the present (as opposed to the past or future).
  • Having high levels of physiological activation (i.e. feeling keyed up).
  • Experiencing what Zimbardo called "sensory input overload" (for example, being at a concert or party with blaring music).
  • Being in a new situation.
  • Being under the influence of alcohol or drugs.

Importantly, not all of these factors need to occur in order for someone to experience deindividuation—but each of them makes experiencing deindividuation more likely. When deindividuation occurs, Zimbardo explains, people experience "changes in perception of self and others, and thereby to a lowered threshold of normally restrained behavior." According to Zimbardo, being deindividuated isn't inherently negative: the lack of restraints could lead people to express positive feelings (such as love). However, Zimbardo described ways in which deindividuation can lead people to behave in violent and antisocial ways (such as stealing and rioting, for example).

Deindividuation Research: An Example

If you've gone trick-or-treating, you may have seen a house where there was a bowl of candy and a note: "Please only take one." In a situation like this, you may have wondered: how often do people actually follow the rules and only take one candy, and what might drive someone to break the rules? A 1976 paper by psychologist Edward Diener and his colleagues suggested that deindividuation could play a role in situations like this.

On Halloween night, Diener and his colleagues asked households from the Seattle area to participate in a deindividuation study. At participating households, a female experimenter would meet each group of children. In some cases—the individuated condition—the experimenter would ask each child for their name and address. In the deindividuated condition, this information was not requested, so the children were anonymous to the experimenter. The experimenter then said that she had to leave the room, and that each child should take just one piece of candy. In some versions of the study, the experimenter added that one child would be held responsible if anyone in the group took extra candy.

The researchers found that Zimbardo's conditions for deindividuation were related to whether or not the children took extra candy (or even helped themselves to coins from a nearby bowl). First, it made a difference whether children were alone or in groups (in this case, the researchers didn't experimentally manipulate group size: they simply recorded whether the children had approached the house individually or as a group). Children who were by themselves were less likely to take extra candy, compared to children who were in groups. Additionally, it mattered whether children were anonymous or individuated: children were more likely to take extra candy if the experimenter didn't know their name. Finally, the researchers found that whether or not someone was held responsible for the group's actions also impacted the behavior of group members. When someone in the group was held responsible—but the experimenter didn't know anyone's name—children were more likely to take extra candy. However, if the experimenter knew the name of the child who would be held responsible, children were less likely to take extra candy (presumably to avoid getting their friend in trouble), and, if the experimenter knew everyone's name, taking extra candy was even less likely.

Social Identity Theory's Explanation of Deindividuation

Another approach to understanding deindividuation comes from social identity theory. According to social identity theory, we derive a sense of who we are from our social groups. People readily categorize themselves as members of social groups; in fact, social identity researchers have found that even being assigned to an arbitrary group (one created by the experimenters) is enough for people to act in ways that favor their own group.

In a 1995 paper about social identity, researchers Stephen Reicher, Russell Spears, and Tom Postmes suggest that being part of a group causes people to switch from categorizing themselves as individuals to categorizing themselves as group members. When this happens, group membership impacts people's behavior and people are more likely to behave in ways that match the norms of the group. The researchers suggest that this could be an alternate explanation for deindividuation, which they call the social identity model of deindividuation (SIDE). According to this theory, when people are deindividuated, they're not acting irrationally, but rather are acting in ways that take into account the norms of that particular group.

A key implication of SIDE is that we can't actually know how someone will behave as part of a group unless we actually know something about the group itself. For example, SIDE and Zimbardo's theory would make similar predictions for a group attending a fraternity party: both would predict that the partygoers would engage in loud, boisterous behavior. However, the SIDE model would predict that the same group of partygoers would behave very differently if another group identity became salient, for example, taking a test the next morning, the social identity of "student" would predominate, and the test-takers would become quiet and serious.

Reducing Deindividuation

Although psychologists point out that deindividuation isn't necessarily negative, there are some cases where people can act in irresponsible or antisocial ways when they're deindividuated. Fortunately, psychologists have found that there are several strategies to counter deindividuation, which rely on increasing how identifiable and self-aware people feel.

As Diener's Halloween study showed, people are less likely to behave in irresponsible ways if their identity is known—so one way to reduce deindividuation is to do what the experimenter in this study did: have people be identifiable rather than anonymous. Another approach involves increasing self-awareness. According to some researchers, people lack self-awareness when they are deindividuated; consequently, one way to counter the effects of deindividuation is to make people more self-aware. In fact, in some social psychology studies, researchers have induced feelings of self-awareness with a mirror; one study showed that research participants are actually less likely to cheat on a test if they can see themselves in a mirror.

A key tenet of social psychology is that we need to look at people's social context in order to understand their behavior—and deindividuation provides an especially striking example of this phenomenon. However, research also suggests that deindividuation isn't an inevitable consequence of being around others. By increasing people's individual identifiability as well as their self-awareness, it's possible to individuate people who are part of a group.

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