Why Groups and Prejudices Form So Easily: Social Identity Theory

This classic social psychology experiment shows how people [have a need] to form into groups and [how this] promotes discriminatiion against others [not in the group].

People's behaviour in groups is fascinating and frequently disturbing. As soon as humans are bunched together in groups we start to do odd things: copy other members of our group, favour members of own group over others, look for a leader to worship and fight other groups. It is easy to provoke war between groups.

But think about the types of groups you belong to, and you'll realise they differ dramatically. Some groups are more like soldiers in the same unit or friends who have known each other from childhood. Long-standing, tight-knit, protecting each other. Perhaps it's not surprising people in these groups radically change their behaviour, preferring members of their own group over others in many ways.

Other groups, though, are much looser. Supporters of a large sports club, for example, or work colleagues only together on a project for a few months or even a group of people in an art gallery appreciating a painting.

Even if we gain nothing whatsoever to gain from favouring our own group, we favor our group among others.
Out in the real world there's a good reason to favour your own group - normally it is also advantageous to yourself. You protect yourself by protecting others like you.

People build their own identities from their group memberships. For example, think of each of the groups you belong to: say at work, or within your family. Part of who you are is probably defined by these groups. Putting it the other way around: the nature of your group memberships define your identity.

As our group membership forms our identity, it is only natural for us to want to be part of groups that are both high status and have a positive image. Crucially though, high status groups only have that high status when compared to other groups. In other words: knowing your group is superior requires having a worse group to look down upon.

Unequal levels of power between groups fundamentally changes the dynamic between them. Whether it's countries, corporations, or just families, if one group has more power, suddenly the way is open for orchestrated competitions and cooperation, not to mention manipulation. Manipulating other groups, though, is a dangerous game, and weaker groups don't always play by the rules set for them.

Cited from an article by Jeremy Dean Mon, Nov 5 2007