Social Identity Theory: A Brief Summary for Students

Travis DixonRevision and Exam Preparation, Studies and Theories

Social identity theory attempts to explain how belonging to a group can influence our thinking and behaviour (Bigstock).

On the surface, Tajfel and Turner’s social identity theory can seem complex as there are multiple parts and some of the ideas are really abstract. In our themantic approach we try to break it down, lesson-by-lesson so each of the major concepts of social identity theory are introduced gradually.

Like many theories, SIT was inspired by events of World War II which saw extreme examples of prejudice and discrimination.

Remember that one of the first questions you should ask when trying to understand psychological theories is what is the theory trying to explain? Remember that psychology is the study of relationships between variables and behaviour, and most theories are attempts to explain relationships between variables and behaviour.

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So what are the variables affecting behaviour in SIT?

Put simply, the variable is belonging to the group and this can affect the way individuals think and act. There are multiple behaviours, and cognitive processes (thought processes and actions) that can be affected by this social variable.

It’s important to remember that social identity theory was devised to explain inter-group behaviour. Specifically, it helps to explain inter-group conflict, including sources of that conflict like stereotypes, prejudice and discrimination.

By the end of the lessons on SIT (as outlined in IB Psychology: A student’s guide) it’s hoped that you understand how the following are related to the social variable of belong to a group:

  • Social categorization
  • Social Comparison
  • Social identity 
  • Self-esteem
  • Positive distinctiveness
  • Out-group homogeneity 

Other behaviours closely related to this are inter-group competition, stereotypes, prejudice and discrimination. I like to think of it in this order:

Belonging to a Group ⇒ Thought Processes (Cognition) ⇒ Actions (Behaviour)

A group of young people dancing at a disco.

Belonging to a  group can affect our thinking and our behaviour. (Image via bigstock license)

  • Social categorization

This is a cognitive process that simply involves thinking about different groups. You categorize groups of people into out-groups and in-groups. At your school, for instance, you might have the typical American TV show cliched groups, like the jocks, cheerleaders, rockers, punks, etc. Or sports fans might think about fans of different teams as belonging to groups.

When individuals categorize people into groups, they are thinking about in-groups and out-groups. If this initial thought process doesn’t occur, then the following cognitive processes and behaviours can’t be explained by social identity theory.

  • Social Comparison

It’s only natural that after we mentally think about people as belonging to in-groups or out-groups that we would compare these groups. So we categorize (put into groups) and then compare. Categorizing and comparing groups are two cognitive processes that are affected by belonging to an in-group.

  • Social identity 

The social identity part of SIT is related to the idea of “belonging to the group” in the first place. Humans build their sense of personal identity: who we think we are. This can be influenced by many things, like our own sense of who we are and what we value. But it can also be influenced by how we think about the groups we belong to. And this is where our social identity is formed: one way we build our sense of who we are is by thinking about our belonging to particular groups. Moreover, this identity is influenced by the comparisons of our in-groups with other out-groups.

  • Self-esteem

A key part of SIT is the self-esteem hypothesis. Tajfel and Turner posited that humans have a natural desire to build a positive social identity and to build their self-esteem. This can explain the nature of how people make comparisons between in-groups and out-groups. Typically, according to SIT, we want to view our in-groups as being better than out-groups; at the very least we want to have a positive view of our in-groups so we can feel good about belonging to that group. This will help build our self-esteem and give us a positive social identity. Moreover, by viewing our own groups as better than the out-group, or by viewing out-groups in a negative way, we can build our self-esteem by feeling good about our in-group.

  • Positive distinctiveness

The above self-esteem hypothesis is closely related to the idea of positive distinctiveness: we have a desire to make our group different (distinct) and better (positively distinct) from other out-groups. This is closely related to in-group bias, which means we favour members of our in-group over those in the out-group.

  • Out-group homogeneity 

When we are thinking about groups of people, instead of individuals, it’s natural to make generalizations. The out-group homogeneity effect is when we tend to view out-group members as being more similar than our own in-group members. This is a product of the above cognitive processes of social categorization and social comparison.

As a stereotype is a generalization about a group of people, you can see how the out-group homogeneity effect might explain stereotypes.


In summary, according to social identity theory, the social variable of belonging to a group and identifying with that group can influence a number of cognitive processes, including thinking about in-groups and out-groups and comparing them. The desire to boost our self-esteem can lead to particular thought processes and comparisons, such as viewing out-group members negatively and being similar (out-group homogeneity). These cognitive processes can then lead to other behaviours such as discrimination, in-group bias and inter-group competition (as one group tries to show they’re better than the other).

So like most psychological theories, the key to understanding SIT is to:

  1. Know the individual parts of the theory:
    1. variables, cognitive processes and behaviours
  2. Understand how they are related

Creating a mind-map of variables, cognitive processes and behaviours is a good way to process the many ideas that make up social identity theory.