Does Incidental Disgust Amplify Moral Judgment? A Meta-Analytic Review of Experimental Evidence

The role of emotion in moral judgment is currently a topic of much debate in moral psychology. One specific claim made by many researchers is that irrelevant feelings of disgust can amplify the severity of moral condemnation. Numerous researchers have found this effect, but there have also been several published failures to replicate it. Clarifying this issue would inform important theoretical debates among rival accounts of moral judgment. We meta-analyzed all available studies--published and unpublished--in which incidental disgust was manipulated prior to or concurrent with a moral judgment task (k = 50). We found evidence for a small amplification effect of disgust (d = 0.11), which is strongest for gustatory/olfactory modes of disgust induction. However, there is also some suggestion of publication bias in this literature, and when this is accounted for, the effect disappears entirely (d = -0.01). Moreover, prevalent confounds mean that the effect size that we estimate is best interpreted as an upper bound on the size of the amplification effect. On the basis of the results of this meta-analysis, we argue against strong claims about the causal role of affect in moral judgment and suggest a need for new, more rigorous research on this topic.