Moral Disgust:

Microbes, Mating, and Morality - Joshua M. Tybur et al.:

"A third domain of disgust pertains to social transgressions. When asked to generate a list of things that disgust them, people often report anti-social behaviors alongside items and acts that we would categorize as pathogen or sexual disgust (Haidt et al., 1994; Nabi, 2002). These social transgressions broadly include non-normative, often anti-social activities such as lying, cheating, and stealing that harm others directly and/or impose diffuse costs on one’s social group. For example, a sample of Australian psychology students who read vignettes about crimes involving drug trafficking, conning, fraud, or theft were more likely to form disgust words in a word-stem completion task than controls (Jones & Fitness, 2008). And the association between such anti-social behaviors and disgust is not exclusive to Western, English speaking cultures. Haidt et al. (1997) report that, when asked to generate a list of disgust elicitors, a Hebrew speaking woman from Israel cited politicians, a Japanese speaking student from Hiroshima cited verbal abuse, and an English speaking student from Chicago cited child abuse. 

However, some have argued that the term disgust is used to describe social transgressions merely for greater rhetorical effect, and actual responses to such acts may not be related to disgust at all (e.g., Bloom, 2004; Nabi, 2002). This hypothesis can be tested by examining whether pathogen-related acts and common socio-moral violations such as lying, cheating, and stealing activate common neural regions associated with the emotion disgust. Recent fMRI investigations show they do (Moll et al., 2005; Schaich Borg, Lieberman, & Kiehl, 2008). For instance, in Schaich Borg et al. (2008), conjunction analyses revealed that pathogen related acts, incestuous acts, and socio-moral violations all activate a network of brain regions previously reported to be associated with disgust (e.g., the globis pallidus, putamen, caudate head, and amygdala). Behavioral studies also indicate disgust is linked with moral judgments (e.g., Wheatley & Haidt, 2005; Marzillier & Davey, 2004) further suggesting that disgust is not just used metaphorically or rhetorically to describe social transgressions, but instead reflects a response toward multiple elicitors including infection, incest, and iniquity. 

From an evolutionary perspective, avoiding interactions with other individuals who imposed costs on oneself or on members of one’s social network would have been beneficial. Within the social arena, other individuals are capable of inflicting costs in a number of ways; in addition to lying, cheating, and stealing, group members can injure, kill, rape, free ride, denigrate, and cuckold. Such behaviors inflict costs directly, and they can disrupt cooperative relationships, social networks, and group cohesion (Cottrell & Neuberg, 2005). Individuals capable of avoiding those whose actions regularly registered as large net costs would have fared better than those who did not discriminate along this dimension. 

In addition to being elicited by different cues than pathogen and sexual disgust, moral disgust motivates a different behavioral strategy. Whereas pathogen disgust motivates proximal avoidance of perceived infection risks, and sexual disgust motivates avoidance of individuals within the specific context of sexual interactions, moral disgust motivates avoidance of social relationships with norm-violating individuals. As recent research indicates, moral disgust might also underlie motivations to punish norm-violating third parties (e.g., Kurzban, DeScioli, & O’Brien, 2007)."