The contagion heuristic is a psychological heuristic leading people to avoid contact with people or objects viewed as “contaminated” by previous contact with someone or something viewed as bad—or, less often, to seek contact with objects that have been in contact with people or things considered good. For example, we tend to view food that has touched the ground as contaminated by the ground, and therefore unfit to eat, or we view a person who has touched a diseased person as likely to carry the disease (regardless of the actual contagiousness of the disease).
The contagion heuristic includes “magical thinking”, such as viewing a sweater worn by Adolf Hitler as bearing his negative essence and capable of transmitting it to another wearer. The perception of essence-transfer extends to rituals to purify items viewed as spiritually contaminated, such as having Mother Teresa wear Hitler’s sweater to counteract his essence.