Critique of classic deindividuation
Classic deindividuation theory, represented by Zimbardo (1969), held that anonymity in crowds weakens self-awareness and self-control, producing antisocial and impulsive behavior. Reicher (1984) questioned this, showing that in anonymous settings people do not act randomly but follow the norms of whatever group is salient. In a meta-analysis of 60 studies, Postmes and Spears (1998) found weak evidence that deindividuation generally increases antinormative behavior and instead found increased conformity to situational norms.
Two sides of the SIDE model
Reicher and colleagues (1995) set out the SIDE model on the basis of social identity theory. On the cognitive side, when group members cannot identify one another as individuals, individual differences blur and shared group identity becomes more prominent, leading to conformity with group norms. On the strategic side, anonymity hides identity from outside powerholders, letting people express group norms without fear of punishment; conversely, when identity is visible to an outgroup, punishable behavior declines. The effect of anonymity thus depends on who can see what.
Extension to online communication
Spears and Lea (1994) criticized the optimistic view that anonymity in computer-mediated communication erases social cues and brings egalitarian communication, arguing that stereotypes and group boundaries may instead grow stronger. Postmes and colleagues (1998) described SIDE effects in which online anonymity builds rather than breaches social boundaries, and Postmes and colleagues (2001) reported that anonymous online groups conformed more strongly to initially primed norms, which then spread. The model is used to understand group polarization and hate speech in online communities as well as crowd behavior such as rallies and protests.
FAQ
- What is the SIDE model in simple terms?
- Being anonymous does not make people act randomly; it blurs the individual and highlights "our group," so people follow that group's rules more closely.
- How does it differ from classic deindividuation theory?
- Classic theory said anonymity causes loss of control and antisocial behavior; SIDE says anonymity increases conformity to group norms, which may be good or bad.
Sources reviewed: 2026-10-26
References
- Zimbardo, P. G. (1969). The human choice: Individuation, reason, and order versus deindividuation, impulse, and chaos. In W. J. Arnold & D. Levine (Eds.), Nebraska Symposium on Motivation (Vol. 17, pp. 237–307). Lincoln: University of Nebraska Press. The classic deindividuation account that SIDE challenged.
- Reicher, S. D. (1984). Social influence in the crowd: Attitudinal and behavioural effects of de-individuation in conditions of high and low group salience. British Journal of Social Psychology, 23(4), 341–350. Early evidence that anonymity increases conformity when group identity is salient.
- Reicher, S. D., Spears, R., & Postmes, T. (1995). A social identity model of deindividuation phenomena. European Review of Social Psychology, 6(1), 161–198. The core statement of the SIDE model.
- Spears, R., & Lea, M. (1994). Panacea or panopticon? The hidden power in computer-mediated communication. Communication Research, 21(4), 427–459. Applies SIDE to power in computer-mediated communication.
- Postmes, T., & Spears, R. (1998). Deindividuation and antinormative behavior: A meta-analysis. Psychological Bulletin, 123(3), 238–259. A meta-analysis finding little support for antinormative deindividuation.
- Postmes, T., Spears, R., & Lea, M. (1998). Breaching or building social boundaries? SIDE-effects of computer-mediated communication. Communication Research, 25(6), 689–715. Shows online anonymity can reinforce group boundaries.
- Postmes, T., Spears, R., Sakhel, K., & de Groot, D. (2001). Social influence in computer-mediated communication: The effects of anonymity on group behavior. Personality and Social Psychology Bulletin, 27(10), 1243–1254. Experimental test of anonymity and group norms online.