Dynamics of discrimination and prejudice via two types of social contagion

Discriminatory behavior can occur suddenly in association with an external shock that amplifies discrimination and prejudice, such as the election of politicians who tolerate or encourage discrimination. Consequently, discrimination can become more normalized in society. Using population dynamics, we modeled discriminatory behavior and the dynamics of prejudicial attitudes to explain such social shifts. In this model, we consider the propagation of discrimination behaviors via two types of social contagion, including direct or immediate, which is rapidly evoked by observing others’ discriminatory actions (behavior-to-behavior), and indirect or slow, via social learning of prejudice from others’ actions and speech (behavior-to-attitude). The latter mediates people’s behavior, which reflects their prejudice. An analysis of the equilibrium status of this model illustrates how social conditions mediate whether an external shock normalizes discrimination and prejudice beyond what was already established in the society. We show that transitions between stable points caused by external shocks in a bistable system can describe drastic social changes. This bistability emerges when discrimination evokes discriminatory behavior from observers. Then, discrimination inhibitors, such as anti-discriminatory education, determine whether prejudice spreads through discriminatory behavior. This result can contribute to explanations of how societies such as countries or social media spaces exhibit fragility to external shocks, and suggests implications for estimating social parameters linked to discrimination and prejudice in future research.