This article explores how much memes like urban legends succeed on the basis of informational selection (i.e., truth or a moral lesson) and emotional selection (i.e., the ability to evoke emotions like anger, fear, or disgust). The article focuses on disgust because its elicitors have been precisely described. In Study 1, with controls for informational factors like truth, people were more willing to pass along stories that elicited stronger disgust. Study 2 randomly sampled legends and created versions that varied in disgust; people preferred to pass along versions that produced the highest level of disgust. Study 3 coded legends for specific story motifs that produce disgust (e.g., ingestion of a contaminated substance) and found that legends that contained more disgust motifs were distributed more widely on urban legend Web sites. The conclusion discusses implications of emotional selection for the social marketplace of ideas.

What determines which ideas succeed in the social environment as people exchange information and stories with others? In a famous Supreme Court opinion, Oliver Wendell Holmes described how ideas succeed or fail using the metaphor of the economic marketplace: “The best test of truth is the power of the thought to get itself accepted in the competition of the market” ( Abrams v. United States, 1919). Holmes's metaphor of the “marketplace of ideas” embodies two key assumptions—(a) that ideas compete, and (b) that they compete on the basis of their truthfulness. Biologist Richard Dawkins (1976) has proposed a biological metaphor that also assumes that ideas compete...