Mind: Ewwwwwwwww!

What if our moral judgments are driven instead by more visceral human considerations? And what if one of those is not divine commandment or inductive reasoning, but simply whether a situation, in some small way, makes us feel like throwing up?

This is the argument that some behavioral scientists have begun to make: That a significant slice of morality can be explained by our innate feelings of disgust. A growing number of provocative and clever studies appear to show that disgust has the power to shape our moral judgments. Research has shown that people who are more easily disgusted by bugs are more likely to see gay marriage and abortion as wrong. Putting people in a foul-smelling room makes them stricter judges of a controversial film or of a person who doesn't return a lost wallet. Washing their hands makes people feel less guilty about their own moral transgressions, and hypnotically priming them to feel disgust reliably induces them to see wrongdoing in utterly innocuous stories.

... even doing the research in the first place is a radical step. The agnosticism central to scientific inquiry is part of what feels so dangerous to philosophers and theologians. By telling a story in which morality grows out of the vagaries of human evolution, the new moral psychologists threaten the claim of universality on which most moral systems depend — the idea that certain things are simply right, others simply wrong. If the evolutionary story about the moral emotions is correct, then human beings, by being a less social species or even having a significantly different prehistoric diet, might have ended up today with an entirely different set of religions and ethical codes.

Human beings are uniquely squeamish creatures. Even if we eat meat, we're willing to ingest only a minuscule proportion of the world's edible animal species. We're repelled by unfamiliar grooming habits, physical contact with strangers, and even our own bodies — their odor and hair, their adipose tissue and shed skin cells, and every bodily fluid except tears. Not to mention the quease-tinged aversion many people feel toward manipulating genes or cross-dressing or whole categories of sexual activity.

More recent work has turned to the role disgust plays in attitudes about right and wrong. For example, Bloom, working with the psychologists David Pizarro and Yoel Inbar at Cornell University, found that people who score higher on a disgust sensitivity scale (sample question: “I try to avoid letting any part of my body touch the toilet seat in a public restroom, even when it appears clean”) also tend to be more likely, all else being equal, to believe that gay marriage and abortion are wrong.

Studies by other psychologists suggest an unconscious mental link between immorality and actual dirt and infection. In a much-noted 2006 study, Chen-Bo Zhong and Katie Liljenquist found that thinking of a past immoral deed made people want to clean their hands with a disinfectant wipe, and that doing so actually made them feel better afterward about their transgression. Zhong and Liljenquist called it the “Macbeth effect,” after the guilt-stricken hand washing of Lady Macbeth.

Issues like abortion and gay marriage, of course, intimately implicate the body, so it's less surprising that disgust would play a role. But other researchers have found the emotion at work in more abstract moral judgments.

In a study published early last year in the journal Science, a team led by Hanah Chapman, a psychology PhD student at the University of Toronto, looked at disgust and unfairness. Test subjects who played a game and considered the results unfair, the researchers found, reacted with the exact same instinctive facial expression as those exposed to more straightforwardly disgusting stimuli. Unfairness, it seems, can disgust us.

“People don't make that facial expression in anger,” Chapman says, “It's really limited to disgust.”

Haidt has done studies in which he primed people to feel disgusted and then asked them to judge the morality of certain actions. In one study, he had some of his unfortunate test subjects respond to four vignettes related to moral judgment while sitting in a room that had been infused with an ammonium sulfide “fart spray.” The stink, he found, made them harsher judges, not only of body-related questions like whether first cousins should be able to have sex and marry, but whether people should drive to work when they could walk or whether a movie studio should release a morally controversial film.

In another study, Haidt found an even more dramatic result. Using posthypnotic suggestion, he got his subjects to experience a flash of disgust at neutral words (“take” for half of the experimental group, “often” for the others). They then read a short description of a thoughtful, open-minded student council president named Dan. If the description contained their disgust word, however, the subjects took a deep dislike to Dan, and found reasons to condemn his behavior and justify their aversion, reasons that had no connection to the description they had read — “Dan is a popularity-seeking snob,” one said. “It just seems like he's up to something,” said another.

To Haidt, all of these results buttress his belief that moral reasoning is simply an after-the-fact story we create to explain our instinctive emotional reactions, in this case a strongly held but arbitrary feeling of disgust. “Moral reasoning is often like the press secretary for a secretive administration — constantly generating the most persuasive arguments it can muster for policies whose true origins and goals are unknown,” he wrote in a 2007 paper in Science.

Plenty of psychologists and philosophers are not yet willing to consign moral reasoning to press-secretary status, however. Developmental psychologists in particular have long studied how children and adolescents learn moral behavior, and they tend to be skeptical of claims that behavior is driven by emotions like disgust. To them, arguments like Haidt's wildly overgeneralize from a few suggestive studies.

For more, see Ewwwwwwwww! by Drake Bennett, August 15, 2010, at The Boston Globe.