Deindividuation in Psychology: Definition & Examples

Key takeaways

  • Deindividuation is a state in which you become so immersed in the norms of the group that you lose your sense of identity and personal responsibility. An individual relinquishes individual responsibility for actions and sees behavior as a consequence of group norms and expectations.
  • Le Bon was the first to recognize how individuals’ behavior changed in a crowd.
  • Anonymity leads to loss of internal restraints, self-identity and responsibility for our behavior. Conditions that increase anonymity serve to minimize concerns about evaluation by others and weaken normal controls based on guilt, shame or fear.
  • Diffusion of responsibility leads to less feelings of personal guilt when committing aggressive acts.
  • Prentice-Dunn et al. (1982) suggested it was a reduced self awareness rather than simply anonymity that leads to de-individuation. They proposed two types of self-awareness; public, and private.

Definition and Historical Background

Deindividuation is a process where people lose their sense of socialized individual identity and resort to unsocialized and anti-social behavior.

Deindividuation is a state of decreased self-evaluation in a crowd and is one of the most widely-cited effects of social groups (Postmes and Spears, 1998).

Deindividuation is characterized by a lower awareness of the self and one’s individuality. This may result in anti-normative and disinhibited behavior, “what forces crowd members at times to behave in uncivilized and violent ways (Diener, 1976).

Classical Theories

Gustave Le Bon’s crowd theory provides the basis for deindividuation (Postmes, 2001). In The Crowd, Le Bon proposes that anonymity, suggestibility, and contagion can turn groups of people into so-called “psychological crowds.”

The collective mind of the crowd takes that of the individual, and individual crowd members become “irrational, fickle, and suggestible” (Postmes, 2001), and as a result becomes controlled by the crowd’s leader, thus capable of performing anti-normative acts.

Le Bon’s theory of The Crowd came to influence many theories of collective behavior, such as those of Freud, McDougall, Blumer, and Allport.

The 1950s brought a resurgence in popularity for Le Bon’s idea.

Festinger et al. (1952) put Le Bon’s theory of the crowd into scientific terms, describing deindividuation as a state where individuals are not “seen or paid attention to as individuals” and for which “under conditions where the member is not individuated in the group, there is likely to occur of the member a reduction of inner restraints against doing various things.”

Early theorists, such as Festinger (1952), believed that deindividuation occurred when those in a group are not given individual treatment; individuals are unaccountable.

This unaccountability leads to a reduction in inner restraint, increasing behavior that would normally be inhibited. Like Lee Bon, Festinger defined deindividuation as a loss of individuality through submergence in a crowd.

However, to Festinger, this individuality is not replaced by the collective mind. Rather, deindividuation simply releases an individual from their normal moral restraints (Postmes and Spears, 1998).

Philip Zimbardo’s Approach to Deindividuation

Zimbardo did not see deindividuation as solely a group phenomenon, applying deindividualization as broadly as suicide, murder, and hostility in relationships (Postmes and Spears, 1998).

Although he studied anti-social behavior, Zimbardo stressed that deindividuated acts could be prosocial. When individuals had minimal self-observation, self-evaluation, and concern for social evaluation, Zimbardo argued, individuals have a weakening of controls based on guilt, shame, fear, and commitment (Zimbardo, 1969).

Zimbardo (1969) conducted an influential study that inspired the field of deindividuation research as a whole. Researchers clothed one group of participants anonymously in oversized lab coats and hoods and a control group with typical clothes and name tags.

The participants were assigned a task similar to that of the Milgram obedience experiment — to shock a so-called participant (an actor) so long as the researchers demanded that they do so.

Those clothed in the anonymizing white robes shocked these actors for a longer amount of time than individuals in typical clothing (Postmes, 2001). However, Zimbardo reported that a replication of his study — the participants dressed as non-anonymous soldiers this time obtained the opposite results.

Although psychologists widely believed Zimbardo’s methodology to have empirical problems, other experiments conducted nearly identical experiments (Postmes, 1998).

Psychologists such as Edward Diener soon devised less contrived contexts to test the validity of Zimbardo’s findings. Diener believed that Zimbardo and other researchers showed inconsistent support for the deindividuation hypothesis because of a lack of concern with the individual psychological changes of deindividuation (Diener, 1980).

For example, in one study by Diener, Westford, Dineen, and Fraser (1973), participants were required to hit a so-called pacifist (an actor trained to be non-responsive). If deindividuation was held, researchers believed, then there would be greater aggression toward the pacifist in crowds.

However, the results of these studies were inconsistent or even contradictory. In one study, for example, isolated individuals actually displayed more aggression than groups (Postmes and Spears, 1998).

Diener et al. also tested the deindividuation hypothesis in the context of trick-or-treating through a field study. Diener et al. aimed to measure anti-normative behavior (stealing candy) as a function of anonymity and group size). However, the field setting made it virtually impossible to measure the self-awareness of participants.

In Prentice-Dunn and Rogers (1982), individuals were instructed to focus attention outward by being seated in a dimly lit room with loud music playing, where participants played video games and were encouraged to speak among each other.

Those in an inward-facing group played less arousing games in a well-lit quiet room. In the former condition, consistent with deindividuation theory, participants had higher levels of aggression (Postmes, 2001).

Criticism and Reconceptualization

Historically, evaluating the research relating to deindividuation has been difficult, as the definition of deindividuation has evolved rapidly. Researchers have seen deindividuation theory as neglecting how crowd behavior may be the product of local group norms.

As late as the 1970s, deindividuation was a focus of psychological research, but there remained little empirical support for deindividuation theory. The evidence supporting deindividuation driven by anonymity was inconsistent, and there remained no evidence for the state of deindividuation itself (Diener, 1980).

As a result, the next decade saw a reconceptualization of deindividuation theory. The main contributing factor in anti-normative behavior in deindividuated groups shifted from a lack of accountability among group members to the anonymity that belonging to the group brings.

According to Le Boon, collective behavior is always irrational, and individuals in the crowd lose their intellectual control. However, sociologists beyond Le Bon found that crowds can actually encourage norms for restraint and orderly behavior (Turner and Killian, 1972).

Theorists postulated that group behavior was a consequence of local group norms rather than the anonymization of individuals within groups. Johnson and Downing 1979 tested this hypothesis by recreating Zimbardo’s original experiment and dressing participants in uniforms similar to that of the Ku Klux Klan or nurses.

Those dressed as Ku Klux Klan members shocked actors more, and those dressed as nurses shocked actors less than the control group. Thus, this research supports the idea that those in groups are sensitive to and highly influenced by normative cues.

Prentice-Dunn et al. (1982) suggested it was a reduced self awareness rather than simply anonymity that leads to de-individuation. They proposed two types of self-awareness.

Public self-awareness

The individual’s concern about the impression presented to other people, knowing that they will be evaluated. This is reduced by being in a crowd, diffusion of responsibility, anonymity, and role models within the group, which set the social norms.

Loss of public awareness leads to loss of public standards of behavior or a lowering of inhibitions. If an individual is self-focused, they act according to their own values, so aggressive behavior is less likely.

Private self- awareness

Concern individuals have for their own thoughts and feelings. This is reduced by becoming so involved with group activities that individuals “forget” themselves.

Loss of private awareness leads to a loss of internal standards and an over-reliance on environmental cues. If an individual is focused on a group, their private self-awareness is decreased, and they are less able to monitor their own behavior, so aggressive behavior is more likely.

Postmes and Spears’ 1998 review, Deindividuation and antinormative behavior, a meta-analysis, showed little support for the occurrence of deindividuated, antinormative behavior or the existence of a deindividuated state.

However, this analysis went on to show that groups and individuals conform more to norms specific to a situation while “deindividuated.”

Prentice-Dunn and Rogers (1982) attempted to account for the inconsistencies in deindividuation theory by extending the theory further into “differential self-awareness theory.”

According to differential self-awareness theory, there are two types of cues that disinhibit collective behavior.

“Accountability cues,” such as anonymity and diffusion of responsibility, decrease public self-awareness, resulting in crowd members being less concerned with self-evaluation and not expecting negative consequences for their behavior.

Conversely, “attentional cues,” such as group cohesiveness and physiological arousal, draw attention away from oneself and one’s own behavior, resulting in decreased self-regulation and attention to personal standards for behavior.

Although both accountability cues and attentional cues can result in antinormative, disinhibited behavior, only reduced private self-awareness could lead to deindividuated behavior, as defined by Prentice-Dunn and Rogers (1989).

Social Identity Theory’s Explanation of Deindividuation

The definition and usage of deindividuation have shifted markedly over time. Early deindividuation theorists such as Frestinger et al. (1952) define deindividuation as associated with not being scrutinized or accountable when in a group.

Zimbardo (1969) later attempted to define the inputs leading to and subsequent effects of deindividuation.

Zimbardo (1969) extended Festinger’s theory of deindividuation to create a theoretical framework specifying the variables leading to deindividuation and output behavior.

The factors leading to deindividuation in the 1960s expanded from sole anonymity to contextual factors such as reductions of responsibility, arousal, sensory overload, a lack of predictability, and the effects of drugs and alcohol (Zimbardo, 1969).

The behavior created by these factors is “in violation of established norms of appropriateness.” In particular, Zimbardo characterized deindividuated behavior as emotional, impulsive, irrational, regressive, and intense.

This deindividuation involved reduced feelings of self-observation but accountability to an audience. And finally, Diener saw reduced self-awareness as being the defining feature of deindividuation. Diener ultimately expanded deindividuation theory but kept it within the realm of classical deindividuation theory.

In contrast, Prentice-Dunn and Rogers (1982) eliminated the anonymity that results in a lack of conscious accountability, resulting in fear of negative consequences.

Social identity theorists argue that a deindividuation situation does not cause a loss of self but a shift in identity from an individual to a member of a crowd.

For example, the collective identity of a group of protestors may prove to unite demonstrators who otherwise have strong divisions between them; and conversely, the entire group may revolt if another group (e.g., police officers) attempts to act on the entire group as if it were one (Reicher et al., 1995).

The most dominant social identity theory of deindividuation is the social identity model of deindividuation effects (SIDE). The SIDE model argues that the factors that lead to deindividuation, such as anonymity, group cohesiveness, and group immersion, can reinforce group salience and conformity to group norms (Postmes and Spears, 1998).

Furthermore, the SIDE model predicts conformity to the social norms of a specific group or social identity rather than conformity to general norms.

The SIDE model can explain the outcomes of several deindividuation experiments.

For example, the SIDE model may attribute the more aggressive behavior while playing video games in a dark room with loud rock music as a consequence of male college student participants believing that aggression was expected and consistent with their group identity in that situation (Postmes and Spears, 1998), and placing participants in front of, for example, a mirror, could focus attention on individual identity (Froming, Walker, and Lopyan, 1982; Postmes and Spears, 1998).

Being aware of one’s individuality can also moderate how participants see each others’ norms. For example, in Froming et al. (1982) — the experiment where participants shocked actors — participants low in private self-awareness shocked more when they believed other people favored shocking more and less when they believed other people shocked less.


Deindividuation, at its extremes, is responsible for the collective behavior of violent crowds, such as lynch mobs, as well as mass social phenomena, such as genocide, stereotyping, and disinhibited behavior online.

Collective Responses to Health Crises

Lewis, Himmelberger, and Elmore (2020) examined the effects of self-reflection on pro-social behavior, citing the COVID-19 pandemic as a possible application.

Wearing surgical masks, according to Mullen et al. (2003), decreases self-awareness and increases the likelihood of selfish behavior (Miller and Rowold, 1979), and the increasing anonymized interactions of those during the pandemic may have led to deindividuation.


Researchers such as Staub (1989) believe that deindividuation is a necessary factor leading to genocide. Hitler and Mouselllini both studied the likes of Le Bon’s crowd theory in creating their programs of mass internment and murder (Postmes and Spears, 1998).

By encouraging deindividuation among members of a group, these individuals become less self-aware, less responsible for their actions, and, therefore, more likely to engage in violence.

Authoritarian governments often create organizations and military groups designed to enhance deindividuation. For example, uniforms and clearly prescribed rules for behavior can facilitate individuals committing acts of violence by enhancing deindividuation through conformity and diffusion of responsibility (Woolf and Hulsizer, 2007).

Such examples of groups promoting deindividuation through these means were Hitler’s youth and the Khmer Rouge.
Such groups, such as those of the SS, required and inculcated an extreme willingness to endure danger and submit to authority, demanding to fight and kill from the start.

The shared training, experience, and privileges of those in these authoritarian organizations promoted strong group ties, and ordinary rules and prohibitions did not apply to members of the SS legally.

As a result, the SS encouraged deindividuation and, subsequently, collective actions that broke down moral prohibitions to mass murder (Staub, 1989).

The Internet

There have been a number of studies examining the impacts of deindividuation on anti-normative behavior over computer-mediated communication, such as the internet.

In particular, Lee (2007) studied how deindividuation affects group polarization while communicating via a computer. Participants either shared personal information (individuated) or remained completely anonymous (deindividuated) before sharing options on several social problems.

Those who were deindividuated tended to identify more strongly with their partner and defended their arguments more strongly when compared with “public” evaluations, which is consistent with the SIDE model of deindividuation.

Deindividuation on the internet is also associated with individuals committing illegal acts.

For example, Hinduja (2008) found that those who experience and prefer anonymity and pseudonymity while using the internet were more likely to pirate software than others.

Reducing Deindividualization

Those with greater levels of self-awareness show lower rates of anti-normative behavior because of deindividuation. This self-awareness has often been simulated by mirrors (Postmes and Spears 1998).

For example, students who take tests in front of mirrors cheat at lower rates than those who do not (Diener and Wallbom, 1976).


Diener, E., Fraser, S. C., Beaman, A. L., & Kelem, R. T. (1976). Effects of deindividuation variables on stealing among Halloween trick-or-treaters. Journal of personality and social psychology, 33(2), 178.

Diener, E., Lusk, R., DeFour, D., & Flax, R. (1980). Deindividuation: Effects of group size, density, number of observers, and group member similarity on self-consciousness and disinhibited behavior. Journal of personality and social psychology, 39(3), 449.

Diener, E., & Wallbom, M. (1976). Effects of self-awareness on antinormative behavior. Journal of Research in Personality, 10(1), 107-111.

Diener, E., & Wallbom, M. (1976). Effects of self-awareness on antinormative behavior. Journal of Research in Personality, 10(1), 107-111.

Diener, E., Westford, K. L., Dineen, J., & Fraser, S. C. (1973). Beat the pacifist: The deindividuating effects of anonymity and group presence. Paper presented at the Proceedings of the Annual Convention of the American Psychological Association.

Froming, W. J., Walker, G. R., & Lopyan, K. J. (1982). Public and private self-awareness: When personal attitudes conflict with societal expectations. Journal of Experimental Social Psychology, 18(5), 476-487.

Hinduja, S. (2008). Deindividuation and internet software piracy. CyberPsychology & Behavior, 11(4), 391-398.

Lee, E.-J. (2007). Deindividuation effects on group polarization in computer-mediated communication: The role of group identification, public-self-awareness, and perceived argument quality. Journal of communication, 57(2), 385-403.

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Postmes, T., & Spears, R. (1998). Deindividuation and antinormative behavior: A meta-analysis. Psychological bulletin, 123(3), 238.

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Reicher, S. D., Spears, R., & Postmes, T. (1995). A social identity model of deindividuation phenomena. European review of social psychology, 6(1), 161-198.

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Staub, E. (1989). The roots of evil: The origins of genocide and other group violence: Cambridge University Press.

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Saul Mcleod, PhD

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Educator, Researcher

Saul Mcleod, Ph.D., is a qualified psychology teacher with over 18 years experience of working in further and higher education.

Charlotte Nickerson

Research Assistant at Harvard University

Undergraduate at Harvard University

Charlotte Nickerson is a student at Harvard University obsessed with the intersection of mental health, productivity, and design.