What is deindividuation in simple terms?

It is the tendency to do things one would not normally do when wearing a mask or blending into a large crowd where it is hard to tell who is who.

Does deindividuation always lead to bad behavior?

No. Research suggests that anonymity does not simply make people aggressive but makes them follow whatever group norms are salient in the situation. When the group norm is prosocial, more helpful behavior can result.

Deindividuation

🧠 Psychology By CampusDown Wiki Editorial Team Last updated October 27, 2026 Views 6

Deindividuation is the phenomenon in which, when anonymity rises and responsibility is diffused in a crowd or group, people become less aware of themselves as distinct individuals and act outside their usual norms and self-control. Conceptualized in 1952 by Leon Festinger and colleagues and developed experimentally by Philip Zimbardo and Ed Diener, it was later reinterpreted from a social identity perspective as conformity to group norms rather than a loss of norms, leading to research on crowd behavior and online behavior.

Contents

1. Origins of the concept
2. Experiments and self-awareness theory
3. The social identity model and online behavior
4. FAQ
5. References

Origins of the concept

In The Crowd, Le Bon (1895) described how individuals in a crowd lose reason and become primitive and impulsive through anonymity, contagion and suggestibility. Festinger, Pepitone and Newcomb (1952) brought this idea into experimental psychology, proposing that inner restraints weaken when individuals in a group are not singled out for attention, a state they called deindividuation. Zimbardo (1969) reported that female students made anonymous with hoods and baggy coats delivered longer electric shocks to others than those wearing name tags. He argued that conditions such as anonymity, diffused responsibility, arousal and sensory overload weaken self-observation and evaluation, producing impulsive behavior. Watson (1973) reported from cross-cultural data that societies in which warriors painted their faces or bodies or wore masks before battle tended to treat enemies more brutally.

Experiments and self-awareness theory

Diener, Fraser, Beaman and Kelem (1976) observed children trick-or-treating on Halloween. When they were not asked their names and addresses and came in groups, children more often violated the instruction to take only one candy and took extra candy or money. Diener (1980) explained deindividuation as a lack of self-awareness: when people are immersed in a group and attention is directed outward, they fail to check behavior against their own standards. Mann (1981) analyzed newspaper accounts of threatened suicides and reported that crowds were more likely to bait the person to jump when they were larger and when it was dark. Johnson and Downing (1979), however, found that participants made anonymous in nurses' uniforms actually reduced shocks, suggesting that situational cues and norms may matter more than anonymity itself.

Reicher, Spears and Postmes (1995) proposed the social identity model of deindividuation effects (SIDE). According to this model, anonymity does not make people lose norms but makes group identity more salient than personal identity, strengthening adherence to the group's norms. A meta-analysis of 60 studies by Postmes and Spears (1998) found weak evidence that deindividuating conditions increase general antinormative behavior, and instead found increased conformity to situation-specific group norms. Postmes, Spears and Lea (1998) argued that anonymity in computer-mediated communication can reinforce group boundaries, and Suler (2004) described the online disinhibition effect, in which anonymity, invisibility and related factors lead people to act with less restraint online. Deindividuation is studied alongside social identity theory, the Stanford prison experiment and social loafing to understand individual behavior in groups.

FAQ

What is deindividuation in simple terms?: It is the tendency to do things one would not normally do when wearing a mask or blending into a large crowd where it is hard to tell who is who.
Does deindividuation always lead to bad behavior?: No. Research suggests that anonymity does not simply make people aggressive but makes them follow whatever group norms are salient in the situation. When the group norm is prosocial, more helpful behavior can result.

Sources reviewed: 2026-10-26

References

Le Bon, G. (1895). Psychologie des foules. Paris: Félix Alcan.
Festinger, L., Pepitone, A., & Newcomb, T. (1952). Some consequences of de-individuation in a group. Journal of Abnormal and Social Psychology, 47(2, Suppl.), 382–389.
Zimbardo, P. G. (1969). The human choice: Individuation, reason, and order versus deindividuation, impulse, and chaos. Nebraska Symposium on Motivation, 17, 237–307.
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), 178–183.
Watson, R. I., Jr. (1973). Investigation into deindividuation using a cross-cultural survey technique. Journal of Personality and Social Psychology, 25(3), 342–345.
Diener, E. (1980). Deindividuation: The absence of self-awareness and self-regulation in group members. In P. B. Paulus (Ed.), Psychology of Group Influence (pp. 209–242). Hillsdale, NJ: Erlbaum.
Johnson, R. D., & Downing, L. L. (1979). Deindividuation and valence of cues: Effects on prosocial and antisocial behavior. Journal of Personality and Social Psychology, 37(9), 1532–1538.
Mann, L. (1981). The baiting crowd in episodes of threatened suicide. Journal of Personality and Social Psychology, 41(4), 703–709.
Reicher, S. D., Spears, R., & Postmes, T. (1995). A social identity model of deindividuation phenomena. European Review of Social Psychology, 6(1), 161–198.
Postmes, T., & Spears, R. (1998). Deindividuation and antinormative behavior: A meta-analysis. Psychological Bulletin, 123(3), 238–259.
Postmes, T., Spears, R., & Lea, M. (1998). Breaching or building social boundaries? SIDE-effects of computer-mediated communication. Communication Research, 25(6), 689–715.
Suler, J. (2004). The online disinhibition effect. CyberPsychology & Behavior, 7(3), 321–326.

Reports and materials that use this theory (Korean)

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This article was last updated on October 27, 2026. It is based on widely recognized original works and textbooks; when citing it in a paper, please check the original sources listed in the references.