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Internalization of societal stereotypes as individual prejudice

How do stereotypic messages about social groups become internalized in an individual’s own preferences and behaviors? We proposed that exposure to such group messages influences how we learn from individual group members in subsequent direct interactions. In a series of experiments, participants interacted with players from two groups, described with positive or negative stereotypes, in a monetary sharing game. Although the actual sharing rates of individual players were equated between groups, stereotypic messages biased how participants learned from and interacted with individual players—a pattern not evident in deliberative decisions or explicit beliefs regarding players’ sharing rates. Computational models revealed that this group preference reflected a combination of biased priors and biased reward updating: stereotypes set participants’ initial expectancies about group members’ behaviors and impaired their ability to learn through direct interaction and feedback. Next, we found that the expression of this bias in a direct learner’s behavior is unwittingly propagated to naïve observational learners, who come to show bias in their own behaviors. In a final set of experiments, we demonstrated this pattern of internalization and propagation when a stereotypic message is attributed to a political leader (Donald Trump), even among participants with opposing political views. These findings offer the first mechanistic account of how explicit messages about group stereotypes and inequalities may be internalized in an individual’s mind as prejudice, from where it is expressed implicitly and propagated to others.