Is purity a distinct and homogeneous domain in moral psychology?

"No" is our answer to the question in our title. In moral psychology, a purity violation (defined as an immoral act committed against one's own body or soul) was theorized to be a homogeneous moral domain qualitatively distinct from other moral domains. In contrast, we hypothesized heterogeneity rather than homogeneity, overlapping rather than distinct domains, and quantitative rather than qualitative differences from other hypothesized domains (specifically, autonomy, which is harm to others). Purity has been said to consist of norms violations of which elicit disgust and taint the soul. Here we empirically examined homogeneity: whether violations of body (e.g., eating putrid food) belong in the same moral domain as violations of the soul unrelated to bodily health (e.g., selling one's soul, desecrating sacred books). We examined distinctness: whether reactions to purity violations differ in predicted ways from those to violations of autonomy. In four studies (the last preregistered), American Internet users (in Studies 2 and 4, classified as politically conservative or liberal; Ns = 80, 96, 1,312, 376) were given stories about violations based on prior studies. Nonhealth purity violations were rated as relatively more disgusting, but less gross (the lay term for the reaction to putrid things) and more likely to taint the soul than were health-related ones. Surprisingly, both health and nonhealth purity violations were typically judged as only slightly immoral if at all. Autonomy violations were rated as more disgusting and tainting of the soul than were purity violations. (PsycInfo Database Record (c) 2023 APA, all rights reserved).