Learning of social norms can lead to a persistent perceptual bias: A diffusion model approach

Abstract

In his seminal studies, Sherif (1935) showed that social norms can induce persistent changes in perceptual decisions. So far, however, the underlying mechanisms are not understood. Specifically, it is unclear whether social norms can lead to a persistent perceptual bias. Using a diffusion model analysis, we extended the social reinforcement account (social norms work via mechanisms of reinforcement learning). Thereby, our study is the first to disentangle whether the effect of social norms on perceptual decision-making is due to altering the uptake of sensory information (i.e., a perceptual bias) or due to shifting the decision criteria (i.e., a judgmental bias). Across two experiments, our results consistently show that learning of social norms shapes perceptual decision-making due to a lasting perceptual bias towards norm-congruent sensory information. This finding was not moderated by the sociality of the norm, that is, by how strongly norms were linked to group membership. Complementary to current psychological models, our results suggest that social norms might become and remain internalized because individuals are chronically biased towards norm-congruent information.