Many moral buttons or just one? Evidence from emotional facial expressions

We investigated whether moral violations involving harm selectively elicit anger, whereas purity violations selectively elicit disgust, as predicted by the Moral Foundations Theory (MFT). We analysed participants' spontaneous facial expressions as they listened to scenarios depicting moral violations of harm and purity. As predicted by MFT, anger reactions were elicited more frequently by harmful than by impure actions. However, violations of purity elicited more smiling reactions and expressions of anger than of disgust. This effect was found both in a classic set of scenarios and in a new set in which the different kinds of violations were matched on weirdness. Overall, these findings are at odds with predictions derived from MFT and provide support for "monist" accounts that posit harm at the basis of all moral violations. However, we found that smiles were differentially linked to purity violations, which leaves open the possibility of distinct moral modules.