David McRaney's book You Are Not So Smart: Why You Have Too Many Friends on Facebook, Why Your Memory Is Mostly Fiction, and 46 Other Ways You’re Deluding Yourself presents phenomena which, in our modern view of the supremacy of reason and free will, should not impact humans' behavior. One is the stereotype threat (Chapter 42, pp. 232-3):
"Psychologists Claude Steele and Joshua Aronson conducted a study in 1995 where they had white and black Americans take the Graduate Record Examination. The GRE is a standardized test usd by many colleges to determine whether or not to accept graduate students. ... Steel and Aronson told half of their subjects they were testing for intelligence, which they hypothesized would add an extra level of stress the other half wouldn't feel. When they got back the results, the white students performed about the same whether or not they were told it was a test of how smart they were. The black students, though, primed by the strereotype threat, performed worse in the group who believed the test would reveal their true intelligence. According to Steel and Aronson, the social stigma of being an African-American messed with their minds. Attempting to fight the stereotype, they had unwelcome thoughts walking around and making noise in their brains while they solved word problems and figured fractions. The white students, free from those fears, had more mind space in which to work. This same sort of experiment has been repeated with gender, nationality, and all sorts of conditions. Psychologists call it the stereotype threat. When you fear you will confirm a negative stereotype, it can become a self-fulfilling prophecy not because the stereotype is true, but because you can't stop worrying that you could become an example proving it."