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What does it take to spark prejudice in humans?

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What does it take to fuel prejudice in humans?

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The minimal group paradigm works like this: participants in the experiment are divided into groups on some arbitrary basis. Maybe eye-colour, maybe what kind of paintings they like, or even by tossing a coin. It doesn't matter what the basis for group membership is, as long as everyone gets a group and knows what it is. After being told they are in a group, participants are divided up so that they are alone when they make a series of choices about how rewards will be shared among other people in the groups. From this point on, group membership is entirely abstract. Nobody else can be seen, and other group members are referred to by an anonymous number. Participants make choices such as "Member Number 74 (group A) to get 10 points and Member 44 (group B) to get 8 points", versus "Member Number 74 (group A) to get 2 points and Member 44 (group B) to get 6 points", where the numbers are points which translate into real money.


The effect may be small, but this is a situation where the groups have been plucked out of the air by the experimenters. Every participant knows which group he or she is in, but they also know that they weren't in this group before they started the experiment, that their assignment was arbitrary or completely random, and that the groups aren't going to exist in any meaningful way after the experiment. They also know that their choices won't directly affect them (they are explicitly told that they won't be given any choices to make about themselves). Even so, this situation is enough to evoke favouritism.

So, it seems we'll take the most minimal of signs as a cue to treat people differently according to which group they are in. Tajfel's work suggests that in-group bias is as fundamental to thinking as the act of categorisations itself. If we want to contribute to a fairer world we need to be perpetually on guard to avoid letting this instinct run away with itself.
