Yesterday, PLoS One published a study entitled “The Rationality of Prejudices” by Thomas Chadefaux and Dirk Helbing, which argues that being prejudiced can be an efficient strategy:
We model an 
-player repeated prisoner’s dilemma in which players are given traits (e.g., height, age, wealth) which, we assume, affect their behavior. The relationship between traits and behavior is unknown to other players. We then analyze the performance of “prejudiced” strategies. . .Such prejudiced strategies have the advantage of learning rapidly. . .they perform remarkably well. . .when the population changes rapidly.
The key assumption is right there in the abstract:
We model an -player repeated prisoner’s dilemma in which players are given traits (e.g., height, age, wealth) which, we assume, affect their behavior. (emphasis added)
In short, the researchers are starting with the assumption that the prejudices are true. Continue reading “Prejudice is rational if you assume prejudice is rational”
The Finch and Pea 