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Deindividuation

How People Behave Differently In Groups

Deindividuation is a concept in social psychology used to explain how people may behave differently when they are part of a group than when they are acting as identifiable individuals. Early theories of deindividuation were influenced by ideas about crowd behavior, particularly the work of Gustave Le Bon, and suggested that people could lose their normal sense of individual responsibility when immersed in a crowd. According to the traditional view, anonymity, group immersion, reduced self-awareness, and decreased accountability could make people more likely to behave aggressively or violate ordinary social norms. Russell Spears’s chapter in The Oxford Handbook of Social Influence examines this classic explanation and argues that the research evidence does not strongly support the idea that anonymity automatically causes people to become antisocial or aggressive.

Group Outdoor Meeting
Traditional Theories

The traditional theory of deindividuation is based on the assumption that people normally regulate their behavior through awareness of themselves as individuals. When people become anonymous or psychologically immersed in a group, this individual self-awareness is thought to decrease. The theory therefore predicts that people will become less concerned about personal accountability and more likely to engage in behavior that they would normally avoid. For example, a person who would never shout insults at someone individually might theoretically feel more comfortable doing so while surrounded by a large, anonymous crowd. This explanation has been influential because anonymity and crowd membership are commonly associated with situations in which unusual or extreme behavior can occur.

One important problem with the traditional explanation is that people in groups do not consistently become more aggressive, irrational, or antisocial. Spears points out that a close examination of the deindividuation literature produces mixed findings and contradictions that are sometimes overlooked in textbooks and secondary accounts. If anonymity simply removed people's normal restraints, we would expect anonymous groups to reliably produce more antisocial behavior, but the research does not demonstrate such a straightforward pattern. Instead, what people do while anonymous can depend heavily on the particular social situation and the norms that are operating within the group.

A particularly important piece of evidence comes from the meta-analysis conducted by Tom Postmes and Russell Spears. Their analysis examined 60 independent studies of deindividuation and found little support for the traditional claim that deindividuation produces a general tendency toward antinormative behavior. Instead, the findings indicated that people who were placed in deindividuating situations often became more responsive to the specific norms associated with their situation. This means that anonymity and group immersion may not eliminate social rules but can make the norms of the relevant group or situation more influential.

Regular Social Norms v. Situation-Specific Norms

The distinction between general social norms and situation-specific group norms is essential for understanding the newer approach to deindividuation. A social norm is a shared expectation about how members of a group should think, feel, or behave. Importantly, these norms are not always positive or negative; a group can have norms that encourage cooperation, generosity, hostility, competition, or aggression. If anonymity increases the influence of a group's norms, the resulting behavior will depend on what that group considers appropriate. Therefore, the same conditions that might produce harmful behavior in one group could encourage helpful or cooperative behavior in another group.

The SIDE Model

This perspective leads into the Social Identity Model of Deindividuation Effects, commonly called the SIDE model. The SIDE model was developed by Stephen Reicher, Russell Spears, and Tom Postmes and challenges the assumption that group immersion causes people to simply lose their sense of self. Instead, it distinguishes between the personal self, which emphasizes what makes someone unique, and social identities, which define people in terms of their membership in meaningful social categories. When a particular social identity becomes more salient, people may think of themselves less as unique individuals and more as members or representatives of a group.

The SIDE model therefore changes the meaning of the word “deindividuation.” Under the traditional theory, deindividuation was primarily understood as a loss of individual identity and personal control. Under the social identity approach, anonymity and group immersion can instead make a shared social identity more psychologically important. People may become more likely to follow the norms associated with that identity because the group becomes a more important source of guidance for behavior. In this sense, deindividuation does not necessarily mean that people stop following rules; it can mean that the rules of a particular group become more influential.

Imagine Two Groups

An example can help illustrate this difference. Imagine two anonymous groups placed in the same online environment, where individual members cannot easily identify one another. If the first group develops a norm of helping new members, anonymity might encourage people to participate more strongly in that supportive behavior because their shared group identity becomes important. If the second group develops a norm of insulting outsiders, anonymity could similarly strengthen participation in hostile behavior. The important factor is therefore not simply the absence of personal identification but the social meaning of the group and the norms that members perceive as appropriate.

Computer-Mediated Communication

The SIDE model is especially useful for understanding behavior in computer-mediated communication and online communities. Online environments can make people anonymous, reduce the visibility of individual characteristics, and emphasize shared group memberships. These conditions can sometimes make group identities more noticeable while making individual differences less prominent. Research associated with the SIDE approach therefore examines how anonymity can influence social categorization, group attraction, communication, and conformity to group norms rather than assuming that anonymity automatically causes harmful behavior.

Identity and Visibility

Another important part of the SIDE perspective concerns the relationship between identity and visibility. Being anonymous does not necessarily mean that a person has no identity or no concern about other people's opinions. Instead, anonymity can change which aspects of identity are easiest to express and which audiences have influence over someone's behavior. The strategic side of SIDE examines how the ability to identify or observe group members can affect how openly people express identity-related attitudes and norms. Consequently, the effects of anonymity can depend on who is watching, what identities are relevant, and what individuals want to communicate to an audience.

The difference between the traditional theory and the SIDE model can be summarized as a difference in what each theory expects groups to do to individuals. The traditional theory predicts that becoming anonymous and immersed in a group reduces personal self-awareness and weakens behavioral restraints, which should make people more likely to violate general norms. The SIDE model instead proposes that these conditions can shift attention toward social identity and increase conformity to group-specific norms. The evidence reviewed by Spears supports the latter interpretation more strongly than the idea that deindividuation simply produces irrational or antisocial behavior.

​It is also important to recognize that the revised approach does not claim that anonymity is harmless or that group behavior is always positive. Groups can develop norms that encourage harmful actions, discrimination, harassment, aggression, or extreme attitudes. The key point is that these behaviors should not automatically be explained as the result of people losing their identities or becoming incapable of self-control. Instead, researchers should examine what group identity is salient, what norms are operating, how members understand their relationship to the group, and what the surrounding social context communicates about appropriate behavior.

The Importance of Using Evidence

The concept of deindividuation is therefore useful because it demonstrates how psychological theories can change when researchers reconsider the evidence behind established explanations. The classic theory offered an intuitive explanation for why crowds and anonymous groups sometimes appear to behave in extreme ways, but empirical research did not consistently support its central prediction of generalized antinormative behavior. The meta-analysis by Postmes and Spears and the later development of SIDE shifted attention toward social identity and situation-specific norms. This change illustrates an important principle in psychology: a theory should be evaluated not only by how convincing it sounds but also by whether experimental and meta-analytic evidence consistently supports its predictions.

For studying this topic, one of the most important ideas to remember is that anonymity does not have a single predictable psychological effect. Anonymity can reduce the emphasis placed on personal characteristics while simultaneously increasing the importance of a shared group identity. Once that group identity becomes salient, people may look to group norms for information about how they should behave. Understanding deindividuation therefore requires looking beyond the individual and examining the interaction among anonymity, social identity, group membership, norms, and the broader social situation.

A useful way to apply these ideas is to examine behavior in crowds, online communities, gaming groups, social movements, workplaces, or other collective environments. Instead of asking only whether people are anonymous, ask what group they believe they belong to and what behavior that group considers acceptable. Next, consider whether the situation makes individual identity or group identity more prominent, and determine what consequences members expect from following or violating the group's norms. These questions provide a more complete explanation of collective behavior than simply assuming that people become aggressive or irrational whenever they are anonymous.

Overall, deindividuation has developed from a theory centered on the loss of individual self-awareness into a broader perspective focused on social identity and group influence. The classic account emphasized anonymity, reduced self-awareness, diminished accountability, and the possibility of antisocial behavior, while contemporary approaches emphasize the importance of group norms and social identities. The evidence reviewed by Spears suggests that people in deindividuating situations are not simply freed from social rules; instead, they may become particularly responsive to the norms that are relevant within their social context. Understanding this distinction is central to explaining why the same anonymous or group-based environment can produce very different behaviors among different groups.

​For further study, the primary resource is Russell Spears's chapter, “Deindividuation,” in The Oxford Handbook of Social Influence, which appears on Oxford Academic as Chapter 16 and covers pages 279–298. The chapter was published online on July 7, 2016, and specifically revisits the classic deindividuation literature, evaluates the evidence for its original claims, and presents a social-identity-based reinterpretation. A particularly useful companion reading is Postmes and Spears's 1998 meta-analysis, which provides the empirical foundation for the argument that deindividuation effects are better understood in relation to situation-specific norms.

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