Communicating Moral Motives: The Social Signaling Function of Disgust

Disgust motivates pathogen avoidance, but it is unclear why it is also reported toward moral violations. Previous explanations have focused on identifying the type of violation specific to disgust. Here, we propose that people express disgust toward any type of moral violation in order to communicate particular motives. Unlike anger, which can be seen as self-interested, disgust communicates a more principled, moral motivation. Two experiments show that observers infer more moral motivation from an expression of disgust and more self-interested motivation from anger. Two further experiments testing participants’ own expression decisions demonstrate that disgust is chosen more to show moral concern and anger is chosen to protest harm to one’s self-interest. By shifting focus to the interpersonal effects of emotion expressions, these findings offer a new perspective for understanding the role of disgust in morality.