Haidt has produced some well-known research which shows that conservatives have much more complex moral attitudes than Leftists do. There are a wider range of factors that enter into a conservative's judgment of what is good or bad. Leftists, by contrast, have much more simply determined moral attitudes.
That finding is of course exactly the opposite of what Leftist psychologists preached from 1950 onwards. Leftists wanted to brand conservatives as the simplistic ones -- which is another example of my rule of thumb which says that you can find out what is true of Leftists by looking at what they say about conservatives. They are great projectors in the Freudian sense.
One of the things Haidt found was that conservative judgments were strongly influenced by feelings of disgust. Conservatives are disgusted by such things as mass-murder. How quaint! Haidt says that disgust began as a guardian of the mouth (against pathogens), but then expanded during biological and cultural evolution to become a guardian of the body more generally, and of the social and moral order.
A recent study by Adams et al. mounted an experimental test of Haidt's theory. They exposed people (mostly Christians) to a disgusting smell and looked at how that affected attitudes. Some people got the smell and some did not. They asked did being exposed to a bad smell instantly make you more conservative!
And they extended Haidt's thinking to test whether disgust is a determinant of attitude to homosexuality. In the days before political correctness, disgust at homosexuality was frequently and widely expressed in the community so I felt I knew the outcome of that query in advance.
And so it was. The authors looked at a wide range of conservative attitudes but it was only attitudes to sexual matters in general and homosexuality in particular that were much influenced by disgust. And the issue that produced the biggest differentiation was: "If a close friend of family member were gay, I would support their right to having a same-sex marriage.” The non-disgusted group (those who had not been exposed to the bad small) almost universally supported such marriage. And, reflecting the pressure of what is presently socially acceptable, about half of the disgusted group did too. "Strongly agree" was however much less common among the disgusted (odor-exposed) group. So some (but not all) people became less acceptant of homosexuality amid a bad smell.
To me the notable fact about the research was how little effect the smell had. A few correlations were statistically significant but all were trivial in magnitude. The strongest correlation was with gay marriage attitudes but, as we have seen, the correlation there was a long way from perfect. A large number of people were unaffected by the bad smell and thought gay marriage was just dandy!
The authors drew generally reasonable conclusions:
These data are consistent with theory delineated by Tybur and colleagues , which argues that disgust functions to decrease the occurrence (both in the self and society) of sexual behaviors that are perceived as increasing risk of pathogen transmission. Relatedly, and as noted by Haidt and Graham , conservative attitudes are driven not only by harm avoidance, but also by concerns about purity. According to these theories, shifts toward politically conservative views on sex may be basic, adaptive, and self-protective responses against perceived spread of pathogens or moral threats. When disgust is evoked, the behavioral immune system engages avoidance to prevent infection (e.g., less interpersonal contact ) and appears to moralize sexual conduct in ways that underlie conservative values of purity and sanctity , . As seen in the results of our study, it is possible that exposure to a disgusting odorant caused increased feelings of disgust, which in turn activated the harm avoidance system and motivated a desire for purity (cleanliness). Once these two systems were activated, it is possible that participants began to adopt attitudes that they perceived as decreasing social harm and/or increasing moral purity.This study will undoubtedly be bruited about by Leftists touting it as "proof" that conservatives are irrational. So it should be noted that the researchers did not say that. They in fact saw the role of disgust as healthy and adaptive.
There is a growing literature indicating that disgust has important consequences for political views and policy preferences. In the research presented here, exposure to a disgusting odor caused greater endorsement of conservative views, including: rejecting gay marriage, restricting sex to marriage, disapproving of the use of pornography, and increased beliefs in Biblical truth. Odor induced conservative shifts concerning gay marriage were particularly robust. It is possible that some forms of political conservatism, particularly those related to sex and sexuality, are basic and inherent in some populations and can readily emerge under threatening or taxing conditions , , .
The one issue I would have with the researchers is that they have overgeneralized their findings. They did not find ANYTHING about conservatism in general, despite testing that. And the few correlations they celebrate in their conclusions above were in fact of trivial magnitude. Only the "Gay marriage" correlation was of some substance. It was however nice to have a confirmation that homosexuality is still associated with disgust even amid a tyranny designed to erase such disgust.
There's a journalistic version of the study here. The original journal article is Disgust and the Politics of Sex: Exposure to a Disgusting Odorant Increases Politically Conservative Views on Sex and Decreases Support for Gay Marriage
Posted by John J. Ray (M.A.; Ph.D.).