Social identity is defined as the part of an individual’s self-concept that they derive from their membership in social groups. Unlike personal identity, which emphasizes those aspects of self that are unique to the individual, social identity focuses on the collective aspect of self—as derived from memberships in social groups that we belong to, such as our nationality, religion, a sports team, or a workgroup. The salience of specific social identities impacts our behavior towards those who share group membership with us (ingroup members) and those that do not (outgroup members). For instance, individuals gain a sense of belonging and shared purpose when they share identity with others (“us philosophers” or “us Hindus”), which affects their well-being and mental health as well as their willingness to act on behalf of the group and promote group goals (e.g., people might unite under an environmental group identity to advocate for climate change action). It also shapes how individuals perceive and interact with others they do not share membership with (e.g., psychologists or Christians), helping explain group behavior such as prejudice and hostility towards such outgroups.

History

Minimal group studies, initially conducted by Henri Tajfel in the early 1970s, formed the basis of social identity theory (Tajfel, 1982; Tajfel & Turner, 1979; for recent reviews, see Ellemers et al., 2002; Hornsey, 2008; Jetten et al., 2012). In this paradigm, English schoolboys entered a research lab to allocate points to members of two distinct groups—one supposedly their own and the other not. Participants were assigned to these groups based on trivial criteria (such as a preference for one painting over another). Tajfel and colleagues found that participants would allocate resources more favorably to members of their own group, demonstrating that mere group membership could trigger group behavior in the form of preferencing their own group even in the absence of previously identified factors that typically cause prejudice (e.g., prior conflict, competition, or deep-seated animosities between groups). The minimal group studies elegantly demonstrated that group behavior (i.e., ingroup favoritism), at a very basic level, arises from the cognitive process that allows participants to identify themselves in terms of group membership (Tajfel & Turner, 1979; see also Dunham, 2018). People acted as group members because they could think of themselves as “we” rather than “I.”

Social identity theory mainly focuses on how people’s behavior is influenced by their ingroup’s situation in relation to other groups, making it primarily a theory of intergroup relations. However, it also raises broader questions about the role of social (and personal) identity and the general functioning of social groups. What factors determine which specific social identity shapes our self-concept in any given situation? What are the effects of identifying the self with a particular social identity? These questions were further developed in self-categorization theory, which grew out of social identity theory and focuses more specifically on the cognitive underpinnings of social identity (Turner et al., 1987). For example, self-categorization theory aims to answer questions such as these: When do we see ourselves in terms of our social identity? What factors influence which social identity becomes most central to our self-concept in different situations? And, what outcomes arise from identifying ourselves primarily in terms of a specific social identity?

Core concepts

The social identity approach (encompassing both social identity theory and self-categorization theory) comprises several key concepts that help us understand how group membership influences individual and collective behavior.

Social categorization

Social categorization is the process of classifying people, including ourselves, into groups based on shared characteristics such as ethnicity, nationality, or social roles (Hornsey, 2008; Turner et al., 1987). This mental process simplifies the social world by organizing complex information into categories like “teachers,” “students,” or “athletes,” making it easier to form social connections and expectations [see Concepts].

Social comparison

Social comparison involves assessing our social identities by comparing our groups to others. This process can foster ingroup favoritism, which is when we perceive our group more positively than others, enhancing group cohesion (Hornsey, 2008; Jetten et al., 2012). For example, a university’s alumni might highlight their school’s achievements compared to other institutions to reinforce a shared sense of pride and social identity.

Positive distinctiveness

Positive distinctiveness refers to the desire to achieve a favorable evaluation of one’s group in relation to others. This concept explains why individuals seek to promote their group’s status and value, often by highlighting differences that cast their group in a positive light (Jetten et al., 1996). For instance, national pride during international sporting events can lead to expressions of superiority or uniqueness.

Questions, controversies, and new developments

Initially, a major component of social identity theorizing concerned the self-esteem hypothesis, which suggests that when group members compare their group favorably to another group, this enhances individual self-esteem. Currently, the self-esteem hypothesis has been largely abandoned due to a lack of empirical evidence, with the focus shifting to the conditions under which group membership positively contributes to well-being (Haslam et al., 2018; Jetten et al., 2012).

Second, empirical findings challenge the traditional view that strong group identification directly leads to ingroup bias or favoritism. Researchers have argued against expecting a straightforward relationship between group identification and ingroup favoritism, asserting that situational factors matter (e.g., normative contexts in which competitive settings may heighten bias, whereas cooperative contexts reduce it; Brewer, 1999). These insights suggest that individual, contextual, and societal factors moderate the expression of ingroup bias, necessitating a nuanced approach to understanding social identity impacts.

Finally, new developments in this field have started to explore the dynamic interplay between personal and social identity. Personal identity encompasses individual traits and values and can interact with social identity to shape experiences and self-perception. This interaction can be fluid, with personal identity potentially moderating or shaping the influence of social identity on outcomes (Hornsey & Jetten, 2004; Postmes & Jetten, 2006).

Broader connections

Social identity intersects with various fields. In psychology, it connects with the study of self-concept and identity formation, exploring how group affiliations shape perceptions and behaviors. It also connects with health psychology, clinical psychology, and organizational psychology in helping to understand how social identity impacts health and well-being (Haslam, 2004; Haslam et al., 2018). In sociology, social identity aligns with theories of social structure and collective behavior, examining how group dynamics influence societal norms and cultural practices. In political science, social identity is crucial for understanding, among others, voter behavior, nationalism, and group-based policy preferences. It also plays a role in conflict resolution and peace studies, in which recognizing shared identities can aid in bridging divides.

Furthermore, in neuroscience, research on how the brain processes group-related information provides insights into the cognitive underpinnings of social identity [see Intergroup Neuroscience]. Additionally, social identity theory informs marketing and organizational behavior by analyzing how brand and company affiliations impact consumer behavior and employee engagement. In education, it assists in developing inclusive teaching strategies that respect and integrate diverse group identities (Mavor et al., 2017).

Further reading

• Ellemers, N., Spears, R., & Doosje, B. (2002). Self and social identity. Annual Review of Psychology, 53(1), 161-186. https://doi.org/10.1146/annurev.psych.53.100901.135228

• Hornsey, M. J. (2008). Social identity theory and self‐categorization theory: A historical review. Social and Personality Psychology Compass, 2(1), 204-222. https://doi.org/10.1111/j.1751-9004.2007.00066.x