Infectious Disease Prevalence, Not Race Exposure, Predicts Both Implicit and Explicit Racial Prejudice Across the United States

What factors increase racial prejudice? Across the United States, increased exposure to Black Americans has been hypothesized to increase White Americans’ prejudicial attitudes toward Black Americans. Here we test an alternative explanation: People living in regions with higher infectious disease rates have a greater tendency to avoid out-groups because such avoidance reduces their perceived likelihood of contracting illnesses. Consistent with this parasite-stress hypothesis, we show that both White and Black individuals (N > 77,000) living in U.S. states in which disease rates are higher display increased implicit (automatic) and explicit (conscious) racial prejudice. These results survived the inclusion of several individual- and state-level controls previously used to explain variability in prejudice. Furthermore, showing disease-related primes to White individuals with strong germ aversion increased their explicit, but not implicit, anti-Black/pro-White prejudice. Domestic out-groups, not just foreigners, may therefore experience increased overt forms of prejudice when disease rates are high.