Distinguishing moral disgust and anger using pupillometry and responses to economic behaviours

A growing body of research suggests that our moral judgements are emotional and intuitive rather than carefully reasoned. Anger and disgust are two emotions that are thought to play key roles in driving these moral judgements. However, as both emotions are negative, reported in response to similar scenarios, and usually highly correlated it is often argued that they are not distinct emotional states. To address this, the present research uses two methods of distinguishing moral disgust from moral anger: pupillometry and an economic game. First, across two studies, we found that self- reported feelings of disgust, but not anger, predicted significant pupil dilation to emotionally engaging sounds and images. Second, we used this method to investigate emotional reactions to immoral vignettes, finding that a specific subtype of moral violation—purity violations—increased both disgust and pupil size. This distinguishes moral disgust and moral anger both physiologically and by the violation to which they respond. Finally, to address real examples of immorality which personally affect the participant, we use a novel economic game where the financial gains of participants were affected by the incompetence and potentially harmful financial choices of their teammates. Results indicate that, unlike the hypothetical moral judgements of the previous study, disgust responds to intentional financial harm inflicted on the participant whereas anger responds to incompetence. Additionally, in response to the same behaviours in a group the player was not a part of, there were different emotional responses: both anger and disgust were found in response to harm. Overall, the present research indicates that disgust and anger are usually distinguishable physiologically and by which behaviours they respond to, but they are elicited differently in hypothetical and non-hypothetical moral judgement.