Transmission of societal stereotypes to individual-level prejudice through instrumental learning.

How are societal stereotypes transmitted to individual-level group preferences? We propose that exposure to a stereotype, regardless of whether one agrees with it, can shape how one experiences and learns from interactions with members of the stereotyped group, such that it induces individual-level prejudice-a process involving the interplay of semantic knowledge and instrumental learning. In a series of experiments, participants interacted with players from two groups, described with either positive or negative stereotypes, in a reinforcement learning (RL) task presented as a money-sharing game. Although players' actual sharing rates were equated between groups, participants formed more positive reward associations with players from positively stereotyped than negatively stereotyped groups. This effect persisted even when stereotypes were described as unreliable and participants were instructed to ignore them. Computational modeling revealed that this preference was due to stereotype effects on priors regarding group members' behavior as well as the learning rates through which reward associations were updated in response to player feedback. We then show that these stereotype-induced preferences, once formed, spread unwittingly to others who observe these interactions, illustrating a pathway through which stereotypes may be transmitted and propagated between society and individuals. By identifying a mechanism through which stereotype knowledge can bypass explicit beliefs to induce prejudice, via the interplay of semantic and instrumental learning processes, these findings illuminate the impact of stereotype messages on the formation and propagation of individual-level prejudice.