Ingroup bias is the preferential treatment people give to whom they perceive to be members of their own groups.

Experiments in psychology have shown that people will award others higher payoffs even when the "group" they share seems random and arbitrary, such as having the same birthday, having the same final digit in their US Social Security Number or even been assigned to the same flip of a coin.

Ingroup effects appear to be stronger, however, when the group is smaller relative to another high-power group.

This cognitive bias has been studied extensively by Henri Tajfel . It is considered a group-serving bias.

Compare to outgroup homogeneity bias.

See also

group attribution error, list of cognitive biases.

References

• Tajfel, H. (1970). Experiments in intergroup discrimination. Scientific American, 223, 96-102.
• Brewer, M. B. (1979). Ingroup bias in the minimal intergroup situations: A cognitive motivational analysis. Psychological Bulletin, 86, 307-324.
• Tajfel, H. (1982). Social identity and intergroup relations. Cambridge, England: Cambridge University Press