Slinging political dirt may be something both sides engage in during election season, but for some voters that metaphor may revealsomething more fundamental about their view of the world.

According to a study in the September 2012 issue of Social Psychology

& Personality Science claims to have found "a positive relationship between disgust sensitivity and political conservatism" -- that is, if you're conservative, you're more likely to be disgusted by things you experience. It's a correlation that holds in the samples they tested in the United States and from the rest of the world.

The authors -- Jonathan Haldt (University of Virginia, Charlottesville), Yoel Inbar (Tilburg University), David Pizarro (Cornell University) and Ravi Iyer (University of Southern California) -- looked at a large sample of 31,405 subjects split into two groups, one of participants from the US and one consisting of people from a range of 121 different countries.


In both tests, the subjects were asked questions about political beliefs while near reminders of bodily cleanliness -- that is, being sat near a hand sanitiser dispenser, or being asked to use a hand wipe before responding.

In the first experimental group, there was a clear link between cleanliness and political conservatism, while in the second group respondents were more likely to be critical of unusual sexual behaviour; the control groups, which didn't have reminders of cleanliness, didn't exhibit correlations in belief. The authors concluded that "contamination disgust was strongly correlated with conservatism".

Attempts to find links between political conservatism and some form of "disgust" do tend to pop up every now and again. In 2008,

this study for the US National Institute of Health claimed that "disgust can increase the severity of moral judgments", while this 2004 study in Group Processes & Intergroup Relations found evidence to support the hypothesis that "chronic and contextually aroused feelings of vulnerability to disease motivate negative reactions to foreign peoples". Then there's this 2010 study which finds "disgust is part of a

'behavioral immune system' that promotes socially conservative value systems and can lead to increased negative attitudes toward outgroups" such as homosexuals, and this study from 2008 found the link between disgust and politics was clearest on "purity-related issues -- specifically abortion and gay marriage". The list goes on -- there are numerous similar studies and they broadly find similar trends.


However, a comprehensive paper from 2010 in Evolutionary Psychology assesses several studies on the topic, and "consistently finds no relationship between sensitivity to pathogen disgust and multiple measures of political conservatism" -- that is, if there is a correlation between being conservative and being disgusted, it's not because of some primal desire to avoid disease. It's possibly entirely psychological.

That raises an important issue to consider when this kind of research comes out. It's not uncommon to find political commentators on the left argue that conservatives tend to be against ideas such as gay marriage out of some kind of fear or disgust, but of course it's not true that all conservative voters are motivated by disgust in choosing their beliefs, nor that disgust is necessarily the primary reason for their positions. If people hold beliefs you disagree with, it's better to respond with logic rather than writing them off as being dictated by their gut.

Wired.co.uk previously spoke to Jonathan Haidt, the principal author of this paper, about the "moral dumbfounding" behind our political choices, and the way our moral compasses are be guided by our instincts.