In sickness and in filth: Developing a disdain for dirty people

Cleanliness is universally valued, and people who are dirty are routinely marginalized. In this research, we measured the roots of negative attitudes toward physically unclean individuals and examined the differences that exist in these attitudes between childhood and adulthood. We presented 5- to 9-year-old children and adults (total N = 260) with paired photographs of a dirty person and a clean person, and we measured biases with a selective trust task and an explicit evaluation task. In Study 1, where images of adults were evaluated, both children and adults demonstrated clear biases, but adults were more likely to selectively trust the clean informant. Study 2 instead used images of children and included several additional tasks measuring implicit attitudes (e.g., an implicit association task) and overt behaviors (a resource distribution task) and also manipulated the cause of dirtiness to include illness, enjoyment of filth, and accidental spillage. Children and adults again revealed strong biases regardless of the cause of dirtiness, but only children exhibited a bias on the explicit evaluation task. Study 3 replicated these findings in India, a country that has historically endorsed strong purity norms. Overall, this research indicates that dirty people are targets of discrimination from early in development, that this is not merely a Western phenomenon, and that this pervasive bias is most strongly directed at individuals of similar ages.