New research carried out by psychologists at the University of Kent has shown for the first time that a decision to express disgust or anger depends on the motives a person seeks to communicate.
Previous studies have suggested that the emotion of disgust originally evolved to protect people from infectious disease; people don't generally eat rotten meat, crawling with maggots, because they feel disgusted by the prospect.
But disgust is also associated with immorality and the researchers from the University's School of Psychology set out to establish why this should be, given its disparate origins in disease avoidance.
One prominent answer has been that people are disgusted by immoral acts that lead to feelings of contamination or impurity, but this view is difficult to reconcile with the observation that people also say that they are disgusted by acts like stealing, bullying or cheating.
The Kent researchers, Tom Kupfer and Professor Roger Giner-Sorolla, established that disgust's role in morality is not explained wholly by what people feel when they express disgust in response to an immoral behaviour, but also what they seek to communicate.
In two experiments study participants were asked to consider different scenarios in which a person expressed either anger or disgust. They were then questioned about what they thought was motivating the person expressing each emotion.
The results showed that a person who expresses disgust is judged to be motivated more by impartial, moral, concerns while a person who expresses anger towards the same immoral act is more likely to be motivated by self-interest.
An expression of disgust therefore signals different information to an observer than an expression of anger. Perhaps, then, people express disgust rather than anger when they want to show that they are motivated by moral concerns.
Two further experiments confirmed this: participants themselves were more likely to choose to express disgust when their goal was to show that their condemnation of an act was morally motivated, while they chose to express anger when they sought to protest that the act harmed their own interests.
The findings suggest that disgust is not just an expression of an inner feeling, like nausea or contamination, but a signal that advertises a moral position.
The research has been published in a paper, entitled Communicating moral motives: The social signalling function of disgust, published in the journal Social Psychological and Personality Science. See: http://journals.
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Established in 1965, the University of Kent - the UK's European university - now has almost 20,000 students across campuses or study centres at Canterbury, Medway, Tonbridge, Brussels, Paris, Athens and Rome.
It has been ranked: 23rd in the Guardian University Guide 2016; 23rd in the Times and Sunday Times University Guide 2016; and 22nd in the Complete University Guide 2015.
In the Times Higher Education (THE) World University Rankings 2015-16, Kent is in the top 10% of the world's leading universities for international outlook and 66th in its table of the most international universities in the world. The THE also ranked the University as 20th in its 'Table of Tables' 2016.
Kent is ranked 17th in the UK for research intensity (REF 2014). It has world-leading research in all subjects and 97% of its research is deemed by the REF to be of international quality.
In the National Student Survey 2016, Kent achieved the fourth highest score for overall student satisfaction, out of all publicly funded, multi-faculty universities.
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The University is worth £0.7 billion to the economy of the south east and supports more than 7,800 jobs in the region. Student off-campus spend contributes £293.3m and 2,532 full-time-equivalent jobs to those totals.
In 2014, Kent received its second Queen's Anniversary Prize for Higher and Further Education.