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Social identity theory

Tell people they belong to a group, invent the group five minutes earlier, and they start handing its members the better deal. Henri Tajfel built a theory on that result.

Published November 3, 2026. 3 sources at the foot of the page.

What it says

Social identity theory says part of how a person sees themselves comes from the groups they belong to. People then work to keep those groups looking good by comparison.

It runs in three steps. First a person sorts the world into groups, including their own. Second they take one of those groups on as part of who they are. Third they compare it with others, and a favorable comparison is worth something to them.

The theory then asks what a person does when their group compares badly. Tajfel and John Turner named three routes: leave for a better group, change what the comparison is about, or work to change the group's position.

The three steps, and what follows

The steps are the theory. The last row is the part people usually quote.

  1. Categorization

    Sorting people into groups, including yourself. It is ordinary and useful, and it is where the rest starts.

  2. Identification

    Taking a group on as part of who you are. The standing of the group now affects yours.

  3. Comparison

    Measuring your group against others, with a preference for comparisons your side wins.

  4. Favoring your own side

    Giving your group the better deal, which shows up with no conflict, no history and nothing at stake.

Where it came from

Tajfel's minimal group experiments in the early 1970s stripped a group of everything. Volunteers were split on something trivial, such as which of two abstract painters they preferred. They never met the others. Their task was to divide points between an anonymous member of their own group and one of the other. They favored their own side, and often chose a split that widened the gap over one that gave their own side more.

The full statement came in 1979, in a chapter by Tajfel and Turner. Turner and colleagues extended it into self categorization theory in 1987, which asks when a person thinks of themselves as a group member at all.

What holds up, and what does not

The minimal group effect replicates and is one of the sturdier findings in social psychology. The theory also makes a distinction worth keeping. Favoring your own side is not the same thing as hostility to another, and the first turns up far more readily.

The criticisms are about the laboratory and the size of the thing. The minimal group task gives people little to do except divide points, which may invite the behavior it measures. The size of the effect also depends on how much the group matters to the person. It explains a pull, not a whole society.

What it does not mean

It does not say prejudice is natural or excusable. The theory is about a mechanism that can be arranged. That is why the research on reducing it works on how groups are categorized rather than on telling people to try harder.

Check yourself

Three questions on what is above. Each answer says why.

  1. What makes a minimal group experiment minimal?

    1. The groups are small
    2. The groups have no history, no contact and nothing at stake
    3. Only one group is studied
    Show the answer

    Answer: B. The point is to strip out conflict, contact and interest, and then see whether favoritism appears anyway. It does.

  2. Pick the three steps the theory names, in order.

    1. Comparison, identification, categorization
    2. Categorization, identification, comparison
    3. Identification, comparison, competition
    Show the answer

    Answer: B. Sort the world, take one group on as your own, then compare. The favoritism follows from the third step.

  3. Which statement does the research support?

    1. Favoring your own side and hostility to another are the same thing
    2. Favoring your own side appears more readily than hostility to another
    3. Favoritism needs a real conflict over resources
    Show the answer

    Answer: B. The minimal group work shows favoritism with nothing at stake, and the two tendencies are measured separately.

Sources

  1. Tajfel, H. (1970). Experiments in intergroup discrimination. Scientific American, 223(5).
  2. Tajfel, H., and Turner, J. C. (1979). An integrative theory of intergroup conflict. In W. G. Austin and S. Worchel (Editors), The Social Psychology of Intergroup Relations. Brooks and Cole.
  3. Turner, J. C., Hogg, M. A., Oakes, P. J., Reicher, S. D., and Wetherell, M. S. (1987). Rediscovering the Social Group: A Self Categorization Theory. Blackwell.

Practice it on Learn

Learn teaches Tajfel's minimal group studies in Four more studies that changed the field, the second unit of the Landmark studies track. The unit reads them beside the Little Albert experiment, Pavlov's dogs and learned helplessness, each against its original paper.

Practice Tajfel's minimal group experimentSee what Learn is

Every lesson is free. Plus is optional. For adults 18 and over.

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