The shocking experience of the Holocaust stimulated a multitude of research programs with the objective of identifying and overcoming the causes of intolerance and hostility. Gordon W. Allport (1897–1967), who taught psychology at the Harvard University since 1924, wrote his book The Nature of Prejudice in this historical context. Like many of his colleagues, he felt that his research should be devoted to reducing intolerance against others. The most immediate sociopolitical goal of his research was to repeal the racial segregation exercised in the Confederate States.

In his book, Allport defines ethnic prejudice as “an antipathy based upon a faulty and inflexible generalization. It may be felt or expressed. It may be directed toward a group as a whole, or toward an individual because he is ...