Social identity theory
As originally formulated by social psychologists Henri Tajfel and John Turner in the 1970s and the 1980s, social identity theory introduced the concept of a social identity as a way in which to explain intergroup behaviour. Social identity theory is described as a theory that predicts certain intergroup behaviours on the basis of perceived group status differences, the perceived legitimacy and stability of those status differences, and the perceived ability to move from one group to another. This contrasts with occasions where the term "social identity theory" is used to refer to general theorizing about human social selves. Moreover, and although some researchers have treated it as such, social identity theory was never intended to be a general theory of social categorization. It was awareness of the limited scope of social identity theory that led John Turner and colleagues to develop a cousin theory in the form of self-categorization theory, which built on the insights of social identity theory to produce a more general account of self and group processes.
The term social identity approach, or social identity perspective, is suggested for describing the joint contributions of both social identity theory and self-categorization theory. Social identity theory suggests that an organization can change individual behaviors if it can modify their self-identity or part of their self-concept that derives from the knowledge of, and emotional attachment to the group.
The term 'social identity theory' achieved academic currency only in the late 1970s, but the basic underlying concepts associated with it had emerged by the early twentieth century. William G. Sumner, writing in 1906, captures the primary dynamics in this excerpt from his influential work Folkways: A Study of the Sociological Importance of Usages, Manners, Customs, Mores, and Morals:
- "Loyalty to the group, sacrifice for it, hatred and contempt for outsiders, brotherhood within, warlikeness without,—all grow together, common products of the same situation. ... Men of an others-group are outsiders with whose ancestors the ancestors of the we-group waged war. ... Each group nourishes its own pride and vanity, boasts itself superior, exalts its own divinities, and looks with contempt on outsiders. Each group thinks its own folkways the only right ones, and if it observes that other groups have other folkways, these excite its scorn."
By the late 1920s the collectivist perspective had all but disappeared from mainstream social psychology. Over fifty years later, around the time of the first formal use of the term 'social identity theory', Tajfel wrote this on the state of social psychology:
- "Thus, social categorization is still conceived as a haphazardly floating 'independent variable' which strikes at random as the spirit moves it. No links are made or attempted, between the conditions determining its presence and mode of operation, and its outcomes in widely diffused commonalities of social behaviour. Why, when and how is social categorisation salient or not salient? What kind of shared constructions of social reality, mediated through social categorization, lead to a social climate in which large masses of people feel they are in long-term conflict with other masses? What, for example, are the psychological transitions from a stable to an unstable social system?" (Original emphasis, p. 188)
Thus, social identity theory in part reflects a desire to reestablish a more collectivist approach to social psychology of the self and social groups.
The interpersonal-intergroup continuum
Social identity theory states that social behavior will want a person to change his/her behavior while in a group. It varies along a continuum between interpersonal behavior and intergroup behaviour. Completely interpersonal behaviour would be behaviour determined solely by the individual characteristics and interpersonal relationships that exists between only two people. Completely intergroup behaviour would be behaviour determined solely by the social category memberships that apply to more than two people. The authors of social identity theory state that purely interpersonal or purely intergroup behaviour is unlikely to be found in realistic social situations. Rather, behaviour is expected to be driven by a compromise between the two extremes. The cognitive nature of personal vs. social identities, and the relationship between them, is more fully developed in self-categorization theory. Social identity theory instead focuses on the social structural factors that will predict which end of the spectrum will most influence an individual's behaviour, along with the forms that that behavior may take.
A key assumption in social identity theory is that individuals are intrinsically motivated to achieve positive distinctiveness. That is, individuals "strive for a positive self-concept". As individuals to varying degrees may be defined and informed by their respective social identities (as per the interpersonal-intergroup continuum) it is further derived in social identity theory that "individuals strive to achieve or to maintain positive social identity". The precise nature of this strive for positive self-concept is a matter of debate (see the self-esteem hypothesis). Both the interpersonal-intergroup continuum and the assumption of positive distinctiveness motivation arose as outcomes of the findings of minimal group studies. In particular, it was found that under certain conditions individuals would endorse resource distributions that would maximize the positive distinctiveness of an ingroup in contrast to an outgroup at the expense of personal self-interest.
Positive distinctiveness strategies
Building on the above components, social identity theory details a variety of strategies that may be invoked in order to achieve positive distinctiveness. The individual's choice of behaviour is posited to be dictated largely by the perceived intergroup relationship. In particular the choice of strategy is an outcome of the perceived permeability of group boundaries (e.g., whether a group member may pass from a low status group into a high status group), as well as the perceived stability and legitimacy of the intergroup status hierarchy. The self-enhancing strategies detailed in social identity theory are detailed below. Importantly, although these are viewed from the perspective of a low status group member, comparable behaviours may also be adopted by high status group members.
It is predicted that under conditions where the group boundaries are considered permeable individuals are more likely to engage in individual mobility strategies. That is, individuals "disassociate from the group and pursue individual goals designed to improve their personal lot rather than that of their ingroup".
Where group boundaries are considered impermeable, and where status relations are considered reasonably stable, individuals are predicted to engage in social creativity behaviours. Here, low-status ingroup members are still able to increase their positive distinctiveness without necessarily changing the objective resources of the ingroup or the outgroup. This may be achieved by comparing the ingroup to the outgroup on some new dimension, changing the values assigned to the attributes of the group, and choosing an alternative outgroup by which to compare the ingroup.
Here an ingroup seeks positive distinctiveness and requires positive differentiation via direct competition with the outgroup in the form of ingroup favoritism. It is considered competitive in that in this case favoritism for the ingroup occurs on a value dimension that is shared by all relevant social groups (in contrast to social creativity scenarios). Social competition is predicted to occur when group boundaries are considered impermeable, and when status relations are considered to be reasonably unstable. Although not privileged in the theory, it is this positive distinctiveness strategy that has received the greatest amount of attention.
In-group favoritism (also known as "ingroup bias", despite Turner's objections to the term) is an effect where people give preferential treatment to others when they are perceived to be in the same ingroup. Social identity attributes the cause of ingroup favoritism to a psychological need for positive distinctiveness and describes the situations where ingroup favoritism is likely to occur (as a function of perceived group status, legitimacy, stability, and permeability). It has been shown via the minimal group studies that ingroup favoritism may occur for both arbitrary ingroups (e.g. a coin toss may split participants into a 'heads' group and a 'tails' group) as well as non-arbitrary ingroups (e.g. ingroups based on cultures, genders, sexual orientation, and first languages).
Continued study into the relationship between social categorization and ingroup favoritism has explored the relative prevalences of the ingroup favoritism vs. outgroup discrimination, explored different manifestations of ingroup favoritism, and has explored the relationship between ingroup favoritism and other psychological constraints (e.g., existential threat).
System justification theory was originally proposed by John Jost and Mahzarin Banaji in 1994 to build on social identity theory and to understand important deviations from ingroup favoritism, such as outgroup favoritism on the part of members of disadvantaged groups (Jost & Banaji, 1994; Jost, 2020).
Social identification can lead individuals to engage in prosocial behaviors towards others. Examples include contexts such as food drives  or even shared purchasing patterns, as might occur for motorcycle riders. Interestingly, consumers may have sub-identities that are nested into a larger identity. As a result, "[w]hen consumers identify with the overall community, they assist other consumers. However, consumers are less likely to help consumers in the overall community when identifying with a subgroup".
Reluctance to bet against identity-relevant outcomes
Social identities are a valued aspect of the self, and people will sacrifice their pecuniary self-interest to maintain the self-perception that they belong to a given social group. Political partisans and fans of sports teams (e.g., Republicans and Democrats, or MLB, NFL, NCAA fans) are reluctant to bet against the success of their party or team because of the diagnostic cost such a bet would incur to their identification with it. As a result, partisans and fans will reject even very favorable bets against identity-relevant desired outcomes. More than 45% of N.C.A.A. basketball and hockey fans, for example, turned down a free, real chance to earn $5 if their team lost its upcoming game.
Social identity theory proposes that people are motivated to achieve and maintain positive concepts of themselves. Some researchers, including Michael Hogg and Dominic Abrams, thus propose a fairly direct relationship between positive social identity and self-esteem. In what has become known as the "self-esteem hypothesis", self-esteem is predicted to relate to in-group bias in two ways. Firstly, successful intergroup discrimination elevates self-esteem. Secondly, depressed or threatened self-esteem promotes intergroup discrimination. Empirical support for these predictions has been mixed.
Some social identity theorists, including John Turner, consider the self-esteem hypothesis as not canonical to social identity theory. In fact, the self-esteem hypothesis is argued to be conflictual with the tenets of the theory. It is argued that the self-esteem hypothesis misunderstands the distinction between a social identity and a personal identity. Along those lines, John Turner and Penny Oakes argue against an interpretation of positive distinctiveness as a straightforward need for self-esteem or "quasi-biological drive toward prejudice". They instead favour a somewhat more complex conception of positive self-concept as a reflection of the ideologies and social values of the perceiver. Additionally, it is argued that the self-esteem hypothesis neglects the alternative strategies to maintaining a positive self-concept that are articulated in social identity theory (i.e., individual mobility and social creativity).
In what has been dubbed the Positive-Negative Asymmetry Phenomenon, researchers have shown that punishing the out-group benefits self-esteem less than rewarding the in-group. From this finding it has been extrapolated that social identity theory is therefore unable to deal with bias on negative dimensions. Social identity theorists, however, point out that for ingroup favouritism to occur a social identity "must be psychologically salient", and that negative dimensions may be experienced as a "less fitting basis for self-definition". This important qualification is subtly present in social identity theory, but is further developed in self-categorization theory. Empirical support for this perspective exist. It has been shown that when experiment participants can self-select negative dimensions that define the ingroup no positive–negative asymmetry is found.
It has been posited that social identity theory suggests that similar groups should have an increased motivation to differentiate themselves from each other. Subsequently, empirical findings where similar groups are shown to possess increased levels of intergroup attraction and decreased levels of in-group bias have been interpreted as problematic for the theory. Elsewhere it has been suggested that this apparent inconsistency may be resolved by attending to social identity theory's emphasis on the importance of the perceived stability and legitimacy of the intergroup status hierarchy.
Social identity theory has been criticised for having far greater explanatory power than predictive power. That is, while the relationship between independent variables and the resulting intergroup behaviour may be consistent with the theory in retrospect, that particular outcome is often not that which was predicted at the outset. A rebuttal to this charge is that the theory was never advertised as the definitive answer to understanding intergroup relationships. Instead it is stated that social identity theory must go hand in hand with sufficient understanding of the specific social context under consideration. The latter argument is consistent with the explicit importance that the authors of social identity theory placed on the role of "objective" factors, stating that in any particular situation "the effects of [social identity theory] variables are powerfully determined by the previous social, economic, and political processes".
Some researchers interpret social identity theory as drawing a direct link between identification with a social group and ingroup favoritism. This is because social identity theory was proposed as a way of explaining the ubiquity of ingroup favoritism in the minimal group paradigm. For example, Charles Stangor and John Jost state that "a main premise of social identity theory is that ingroup members will favour their own group over other groups". This interpretation is rejected by other researchers. For example, Alex Haslam states that "although vulgarized versions of social identity theory argue that 'social identification leads automatically to discrimination and bias', in fact…discrimination and conflict are anticipated only in a limited set of circumstances". The likening of social identity theory with social competition and ingroup favouritism is partly attributable to the fact that early statements of the theory included empirical examples of ingroup favouritism, while alternative positive distinctiveness strategies (e.g., social creativity) were at that stage theoretical assertions. Regardless, in some circles the prediction of a straightforward identification-bias correlation has earned the pejorative title "social identity theory-lite". This raises the problem of whether social identity theory really does explain the ubiquity of ingroup favoritism in the minimal group paradigm without making recourse to "the generic norm hypothesis" originally proposed by Tajfel but later abandoned.
- Turner, John; Oakes, Penny (1986). "The significance of the social identity concept for social psychology with reference to individualism, interactionism and social influence". British Journal of Social Psychology. 25 (3): 237–252. doi:10.1111/j.2044-8309.1986.tb00732.x.
- Turner, J. C.; Reynolds, K. J. (2010). "The story of social identity". In T. Postmes; N. Branscombe (eds.). Rediscovering Social Identity: Core Sources. Psychology Press.
- Tajfel, H.; Turner, J. C. (1979). "An integrative theory of intergroup conflict". In W. G. Austin; S. Worchel (eds.). The social psychology of intergroup relations. Monterey, CA: Brooks/Cole. pp. 33–47.
- Tajfel, H.; Turner, J. C. (1986). "The social identity theory of intergroup behaviour". In S. Worchel; W. G. Austin (eds.). Psychology of Intergroup Relations. Chicago, IL: Nelson-Hall. pp. 7–24.
- Turner, J. C. (1999). Ellemers, N.; Spears, R.; Doosje, B. (eds.). "Some current issues in research on social identity and self-categorization theories". Social Identity. Oxford: Blackwell: 6–34.
- Haslam, S. A.; Ellemers, N.; Reicher, S. D.; Reynolds, K. J.; Schmitt, M. T. (2010). Postmes, T.; Branscombe, N. R. (eds.). "The social identity perspective today: An overview of its defining ideas". Rediscovering Social Identity. Psychology Press: 341–356.
- Brown, R. J.; Zagefka, H. (2006). "Choice of comparisons in intergroup settings: the role of temporal information and comparison motives". European Journal of Social Psychology. 36 (5): 649–671. doi:10.1002/ejsp.311.
- Ashmore, R. D.; Deaux, K.; McLaughlin-Volpe, T. (2004). "An organizing framework for collective identity: Articulation and significance of multidimensionality". Psychological Bulletin. 130 (1): 80–114. doi:10.1037/0033-2909.130.1.80. PMID 14717651.
- Haslam, A. S. (2001). Psychology in Organizations. London, SAGE Publications. p 26-57
- Postmes, T. & Branscombe, N. (2010). "Sources of social identity". In T. Postmes & N. Branscombe (Eds). Rediscovering Social Identity: Core Sources. Psychology Press.
- Sumner, W. G. Folkways: A Study of the Sociological Importance of Usages, Manners, Customs, Mores, and Morals. New York: Ginn, 1906. p. 13.
- Hogg, Michael A.; Williams, Kipling D. (1 January 2000). "From I to we: Social identity and the collective self". Group Dynamics: Theory, Research, and Practice. 4 (1): 81–97. doi:10.1037/1089-2618.104.22.168.
- Tajfel, H. (1979). "Individuals and groups in social psychology". British Journal of Social and Clinical Psychology. 18 (2): 183–190. doi:10.1111/j.2044-8260.1979.tb00324.x.
- Tajfel, H. (1978). Tajfel, H. (ed.). "Interindividual and intergroup behaviour". Differentiation Between Groups: Studies in the Social Psychology of Intergroup Relations. London: Academic Press: 27–60.
- Oakes, Penny; Haslam, Alex; Turner, John (1994). Stereotyping and social reality. Blackwell: Oxford.
- Turner, J. C.; Reynolds, K. H. (2001). "The Social Identity Perspective in Intergroup Relations: Theories, Themes, and Controversies". In Brown, S. L.; Gaertner (eds.). Blackwell Handbook of Social Psychology: Intergroup Processes. 3. pp. 133–152. doi:10.1002/9780470693421.ch7.
- Haslam, S. Alexander; Reicher, Stephen D.; Platow, Michael J. (2011). The new psychology of leadership: Identity, influence and power. New York, NY: Psychology Press. pp. 45–76. ISBN 978-1-84169-610-2.
- Long, K.; Spears, R. (1997). Spears, R.; Oakes, P. J.; Ellemers, N; et al. (eds.). "The self-esteem hypothesis revisited: Differentiation and the disaffected". The Social Psychology of Stereotyping and Group Life. Oxford: Blackwell: 273–295.
- Rubin, M.; Badea, C.; Jetten, J. (2014). "Low status groups show in-group favoritism to compensate for their low status and to compete for higher status". Group Processes and Intergroup Relations. 17 (5): 563–576. doi:10.1177/1368430213514122.
- Turner, J. C. (1978). H, Tajfel (ed.). "Social categorization and social discrimination in the minimal group paradigm". Differentiation Between Social Groups: Studies in the Social Psychology of Intergroup Relations. London: Academic Press: 235–250.
- Tajfel, H. (1978). Tajfel, H. (ed.). "The achievement of group differentiation". Differentiation Between Groups: Studies in the Social Psychology of Intergroup Relations. London: Academic Press: 77–100.
- Tajfel, H. (1974). "Social identity and intergroup behavior". Social Science Information. 13 (2): 65–93. doi:10.1177/053901847401300204.
- Miller, D. (1983). Children and race. Sage publications.
- Haslam, A. S. (2001). Psychology in Organizations. London, SAGE Publications. p. 38
- Tajfel, Henri; Billig, M. G.; Bundy, R. P.; Flament, Claude (1971). "Social categorization and intergroup behaviour". European Journal of Social Psychology. 1 (2): 149–178. doi:10.1002/ejsp.2420010202.
- Ouwerkerk, J. W.; Ellemers, N.; de Gilder, D. (1999). Ellemers, N.; Spears, R.; Doosje, B. (eds.). "Group commitment and individual effort in experimental and organizational contexts". Social Identity. Oxford: Blackwell: 184–204.
- Haslam, S. A.; Ellemers, N.; Reicher, S. D.; Reynolds, K. J.; Schmitt, M. T. (2010). Postmes, T.; Branscombe, N. R. (eds.). "The social identity perspective tomorrow: Opportunities and avenues for advance". Rediscovering Social Identity. Psychology Press: 357–379.
- Ellemers, N.; Barreto, M. (2001). "The impact of relative group status: affective, perceptual and behavioural consequences". In Brown, S. L.; Gaertner (eds.). Blackwell Handbook of Social Psychology: Intergroup Processes. 3. pp. 324–343. doi:10.1002/9780470693421.ch16.
- Brewer, Marilynn B. (1 January 1979). "Ingroup bias in the minimal intergroup situations: A cognitive motivational analysis". Psychological Bulletin. 86 (2): 307–324. doi:10.1037/0033-2909.86.2.307.
- Hogg, M.A.; Turner, J.C. (1987). "Intergroup behaviour, self-stereotyping and the salience of social categories". British Journal of Social Psychology. 26 (4): 325–340. doi:10.1111/j.2044-8309.1987.tb00795.x.
- Ahmed, Ali M. (1 June 2007). "Group identity, social distance and intergroup bias". Journal of Economic Psychology. 28 (3): 324–337. doi:10.1016/j.joep.2007.01.007.
- Krumm, Angela J.; Corning, Alexandra F. (1 December 2008). "Who Believes Us When We Try to Conceal Our Prejudices? The Effectiveness of Moral Credentials With In-Groups Versus Out-Groups". The Journal of Social Psychology. 148 (6): 689–709. doi:10.3200/SOCP.148.6.689-710. PMID 19058658.
- Giannakakis, Andrew Erik; Fritsche, Immo (1 January 2011). "Social Identities, Group Norms, and Threat: On the Malleability of Ingroup Bias". Personality and Social Psychology Bulletin. 37 (1): 82–93. doi:10.1177/0146167210386120. PMID 20956355.
- Hackel; Zaki; Bavel. (2017). "Social identity shapes social valuation: evidence from prosocial behavior and vicarious reward". Soc Cogn Affect Neurosci. 12 (8): 1219–1228. doi:10.1093/scan/nsx045. PMC 5597888. PMID 28402506.
- Shipley (2008). "Social Comparison and prosocial behavior: An applied study of social identity theory in community food drives". Psychological Reports. 102 (2): 425–434. doi:10.2466/pr0.102.2.425-434. PMID 18567213.
- Johnson; Massiah; Allen (2013). "Community identification increases consumer-to-consumer helping, but not always". Journal of Consumer Marketing. 30 (2): 121–129. doi:10.1108/07363761311304933.
- Morewedge, Carey K.; Tang, Simone; Larrick, Richard P. (2016-10-12). "Betting Your Favorite to Win: Costly Reluctance to Hedge Desired Outcomes". Management Science. 64 (3): 997–1014. doi:10.1287/mnsc.2016.2656. ISSN 0025-1909.
- Hogg, M. A.; Abrams, D. (1990). Abrams, D.; Hogg, M. A (eds.). "Social motivation, self-esteem, and social identity". Social Identity Theory. Constructive and Critical Advances. London: Harvester Wheatsheaf: 44–70.
- Brown, Rupert (1 November 2000). "Social Identity Theory: past achievements, current problems and future challenges". European Journal of Social Psychology. 30 (6): 745–778. doi:10.1002/1099-0992(200011/12)30:6<745::AID-EJSP24>3.0.CO;2-O.
- Rubin, M.; Hewstone, M. (1998). "Social identity theory's self-esteem hypothesis: A review and some suggestions for clarification". Personality and Social Psychology Review. 2 (1): 40–62. doi:10.1207/s15327957pspr0201_3. hdl:1959.13/930907. PMID 15647150.
- Turner, J. C.; Oakes, P. J. (1997). McGarty, C.; Haslam, S. A. (eds.). "The socially structured mind". The Message of Social Psychology. Cambridge, MA: Blackwell: 355–373.
- Bourhis, R. Y.; Gagnon, A. (2001). "Social Orientations in the Minimal Group Paradigm". In Brown, S. L.; Gaertner (eds.). Blackwell Handbook of Social Psychology: Intergroup Processes. 3. pp. 133–152.
- Turner, J. C. & Reynolds, K. J. (2010). The story of social identity. In T. Postmes & N. Branscombe (Eds). Rediscovering Social Identity: Core Sources. Psychology Press. p. 142
- Reynolds, K. J.; Turner, J. C.; Haslam, S. A.; Ryan, M. K. (2000). "When are we better than them and they worse than us? A closer look at social discrimination in positive and negative domains". Journal of Personality and Social Psychology. 78 (1): 64–80. doi:10.1037/0022-3522.214.171.124. PMID 10653506.
- Brown, R. J. (1984). Tajfel, H. (ed.). The role of similarity in intergroup relations. The Social Dimension. 2. Cambridge: University Press. pp. 603–623. doi:10.1017/CBO9780511759154.012. ISBN 9780511759154.
- Duckitt, John (1992). "5". The social psychology of prejudice. London: Praeger Publishers. pp. 84–90.
- Tajfel, H. (1984). Tajfel, H. (ed.). Intergroup relations, social myths and social justice in social psychology. The Social Dimension. 2. Cambridge: University Press. pp. 695–715. doi:10.1017/CBO9780511759154.016. ISBN 9780511759154.
- Stangor, C.; Jost, J. T. (1997). Spears, R.; Oakes, P. J.; Ellemers, N; et al. (eds.). "Commentary: Individual, group and system levels of analysis and their relevance for stereotyping and intergroup relations". The Social Psychology of Stereotyping and Group Life. Oxford: Blackwell: 336–358.
- Smith, E.R.; Smith, E. R. (1999). "Reconceptualizing social identity: a new framework and evidence for the impact of different dimensions". Personality and Social Psychology Bulletin. 25: 120–135. doi:10.1177/0146167299025001010.
- Operanio, D.; Fiske, S. T. (2001). "Stereotypes: Content, Structures, Processes and Context". In Brown, R.; Geartner, S. (eds.). Blackwell Handbook of Social Psychology: Intergroup Processes. Oxford: Blackwell. pp. 22–44.
- Triandis, H.C.; Trafimow, D. (2001). "Culture and its implications for intergroup behavior". In Brown, S. L.; Gaertner (eds.). Blackwell Handbook of Social Psychology: Intergroup Processes. 3. pp. 367–385. doi:10.1002/9780470693421.ch18.
- Brewer, M. B.; Gaertner, S. L. (2001). "Toward reduction of prejudice: intergroup contact and social categorization". In Brown, S. L.; Gaertner (eds.). Blackwell Handbook of Social Psychology: Intergroup Processes. 3. pp. 451–472. doi:10.1002/9780470693421.ch22.
- Stangor, C.; Jost, J. T. (1997). Spears, R.; Oakes, P. J.; Ellemers, N; et al. (eds.). "Commentary: Individual, group and system levels of analysis and their relevance for stereotyping and intergroup relations". The Social Psychology of Stereotyping and Group Life. Oxford: Blackwell: 346.
- Spears, R.; Doosje, B.; Ellemers, N. (1999). Ellemers, N.; Spears, R.; Doosje, B. (eds.). "Commitment and the context of social perception". Social Identity. Oxford: Blackwell: 59–83.
- McGarty, C (2001). "Social Identity Theory does not maintain that identification produces bias, and self-categorization Theory does not maintain that salience is identification: Two comments on Mummendey, Klink and Brown". British Journal of Social Psychology. 40 (Pt 2): 173–176. doi:10.1348/014466601164777. PMID 11446223.
- Rubin, M.; Hewstone, M. (2004). "Social identity, system justification, and social dominance: Commentary on Reicher, Jost et al., and Sidanius et al". Political Psychology. 25 (6): 823–844. doi:10.1111/j.1467-9221.2004.00400.x. hdl:1959.13/27347.
- Haslam, A. S. (2001). Psychology in Organizations. London, SAGE Publications. p. 40
- Mind Changers: Henri Tajfel's Minimal Groups: BBC Radio programme about the origins of the theory