Distinguishing Disgust – Behavioural and Physiological Markers of Moral and Physical Disgust

Moral disgust is a term often used to describe the emotional response experienced when witnessing or hearing of a moral violation committed by another individual (Rozin et al., 2008). Previous research has suggested that whilst this wording is used in common parlance, the use of the term “disgust” is used metaphorically, rather than reflecting a true experience of something akin to physical disgust (Nabi, 2002). More recently, the investigation of moral emotions has found that intention, content, and mode of presentation of moral violations all contribute to reported disgust, and perceived immorality (Parkinson & Byrne, 2018; Russell & Giner-Sorolla, 2011). It has been found that different types of moral violation are more likely to elicit different emotions, with purity (bodily-moral) violations eliciting disgust, and socio-moral violations more likely to elicit anger (Landmann & Hess, 2018). Despite this, much of the extant research in moral emotions either blends these elicitors, presents more than one violation at once, or does not control for intention, making isolation of the experienced emotion difficult. This thesis therefore aimed to contribute to contemporary moral research by reviewing existing literature on the elicitation of physical and moral disgust and developing a series of stimuli which control for the previous limitations. In doing so, it will be possible to determine if the experience of moral disgust is similar to physical disgust, or instead represents a distinct emotion. Study 1 found that intentional purity violations elicit significantly higher levels of disgust and moral condemnation than non-intentional and physically disgusting matches. Studies 2 and 3 aimed to determine if physiological and behavioural markers match those reported by participants when compared to expected patterns identified in the systematic literature review in order to help identify if moral disgust presents similarly to physical disgust or is distinct. Studies 2 and 3 showed primarily through behavioural data, that self-reported disgust and anger depend on how ambiguous these terms are in moral psychology. The thesis concludes by providing recommendations for further investigation of moral emotions. Specifically, whilst moral disgust might represent a form of disgust separate from that of physical disgust, this distinction might go deeper depending on the type of moral violation. It is not sufficient to suggest socio-moral violations might elicit anger over disgust, but instead that this emotional processing is more complex. To better explore this hypothesis, moral emotions should be investigated in the context of which moral emotions are most useful, as a social signal to others to preserve social cohesion.