Humans and other animals have evolved the emotion disgust as an early line of defence against pathogen threat. Disgust neutralizes the possibility of pathogen transmission by motivating avoidance responses. It has been argued that disgust may serve a range of functions beyond pathogen avoidance, including sexual partner selection (i.e., sexual disgust) and the regulation of social norm violators (i.e., moral disgust). These disgust systems have implications for a range of social psychological phenomena. One emerging area of work suggests that disgust is implicated in aesthetic judgments. Specifically, ugliness judgments may function to alert us to cues of pathogen presence and evoke disgust. The signal detection process in each disgust system is hypersensitive, as failing to detect a threat may lead to high costs. This can lead to stigmatization of people who are wrongly perceived to pose pathogen risk, such as ethnic outgroups or people with facial and bodily disfigurement.
Neuroanatomically, primitive disgust is associated with activation in the anterior insular cortex and the area postrema, whereas more complex disgust is processed in brain regions within the social decision-making network (SDMN). The ventromedial prefrontal cortex (vmPFC)—an area within the SDMN—may be specifically linked to social disgust.