Social Identity Theory

Social identity theory (SIT) 

SIT was developed by Tajfel and his colleagues (Tajfel and Turner 1979) and it it based on four concepts. Social categorization, social identity, social comparison and positive distinctiveness. Social categorization is that we divide the social environment into in-groups and out-groups and belonging to a group creates a feeling of "us vs. them". An example of this would be the minimal group papadigm (Tajfel 1971). In this study a group of British schoolboys were divided into two groups thinking that it was based on if they liked paintings from Klee or Kandinsky. Then they were asked to give out points to both "teams" and the boys showed a strong tendency for choosing to give their in-group way more than the out-group, even if that meant less points for them in total. What this showed is that the participants would rather create a huge gap between them and the out-group than giving both groups more points but having less of a difference between the teams. This supports the idea that we want to increase perceived variability between the in-group and the out-group. Social identity is not the same as personal identity. It is related to how we behave in our in-group or because of our social identity in a specific group. In a competition for example, two individuals can compete as individuals or as members of rival teams. And depending on if they are alone or a part of a team, they will act differently and take different decisions (Fiske and Taylor, 2008). The last two points are social comparison and positive distinctiveness. According to SIT we strive for a positive self-concept. This means that we seek positive social identities to build, maintain and enhance our self-esteem. This may be a result from the process of social comparison which means that we compare our in-group with out-groups. Positive distinctiveness is the motivation to show that our in-group is better than the out-groups. 

Strengths:
SIT has been supported by hundreds of studies which increases its credibility. It also drew the distinction between personal and social identity and explored the ways our basic need to belong affects social interaction. SIT also contributes to explain areas of psychology like stereotypes and intergroup conflict in settings where there was no realistic basis for conflict. 

Limitations: 
Some studies have showed that the increase in self-esteem associated with out-group discrimination is too short-lived to have long lasting effects on how in-group members view themselves (Rubin and Hewstone, 1998). SIT has more to do with situational explanations over dispositional ones. But there are evidence suggestion that individual differences do affect SIT processes.