By NICHOLAS D. KRISTOF
Published: May 27, 2009
NEW YORK TIMEs

http://www.nytimes.com/2009/05/28/opinion/28kristof.html

If you want to tell whether someone is conservative or liberal, what are a couple of completely nonpolitical questions that will give a good clue?

How’s this: Would you be willing to slap your father in the face, with his permission, as part of a comedy skit?

And, second: Does it disgust you to touch the faucet in a public restroom?

Studies suggest that conservatives are more often distressed by actions that seem disrespectful of authority, such as slapping Dad. Liberals don’t worry as long as Dad has given permission.

Likewise, conservatives are more likely than liberals to sense contamination or perceive disgust. People who would be disgusted to find that they had accidentally sipped from an acquaintance’s drink are more likely to identify as conservatives.

The upshot is that liberals and conservatives don’t just think differently, they also feel differently. This may even be a result, in part, of divergent neural responses.

This came up after I wrote a column earlier this year called “The Daily Me.” I argued that most of us employ the Internet not to seek the best information, but rather to select information that confirms our prejudices . To overcome that tendency, I argued, we should set aside time for a daily mental workout with an ideological sparring partner. Afterward, I heard from Jonathan Haidt, a psychology professor at the University of Virginia. “You got the problem right, but the prescription wrong,” he said.

Simply exposing people to counterarguments may not accomplish much, he said, and may inflame antagonisms .

A study by Diana Mutz of the University of Pennsylvania found that when people saw tight television shots of blowhards with whom they disagreed, they felt that the other side was even less legitimate than before.

The larger point is that liberals and conservatives often form judgments through flash intuitions that aren’t a result of a deliberative process. The crucial part of the brain for these judgments is the medial prefrontal cortex, which has more to do with moralizing than with rationality. If you damage your prefrontal cortex, your I.Q. may be unaffected, but you’ll have trouble harrumphing.

One of the main divides between left and right is the dependence on different moral values. For liberals, morality derives mostly from fairness and prevention of harm. For conservatives, morality also involves upholding authority and loyalty — and revulsion at disgust.

Some evolutionary psychologists believe that disgust emerged as a protective mechanism against health risks, like feces, spoiled food or corpses. Later, many societies came to apply the same emotion to social “threats.” Humans appear to be the only species that registers disgust, which is why a dog will wag its tail in puzzlement when its horrified owner yanks it back from eating excrement.

Psychologists have developed a “disgust scale” based on how queasy people would be in 27 situations, such as stepping barefoot on an earthworm or smelling urine in a tunnel. Conservatives systematically register more disgust than liberals. (To see how you weigh factors in moral decisions, take the tests at www.yourmorals.org.)

It appears that we start with moral intuitions that our brains then find evidence to support. For example, one experiment involved hypnotizing subjects to expect a flash of disgust at the word “take.” They were then told about Dan, a student council president who “tries to take topics that appeal to both professors and students.”

The research subjects felt disgust but couldn’t find any good reason for it. So, in some cases, they concocted their own reasons, such as: “Dan is a popularity-seeking snob.”

So how do we discipline our brains to be more open-minded, more honest, more empirical? A start is to reach out to moderates on the other side — ideally eating meals with them, for that breaks down “us vs. them” battle lines that seem embedded in us . (In ancient times we divided into tribes; today, into political parties.) The Web site www.civilpolitics.org is an attempt to build this intuitive appreciation for the other side’s morality, even if it’s not our morality.

“Minds are very hard things to open, and the best way to open the mind is through the heart,” Professor Haidt says. “Our minds were not designed by evolution to discover the truth; they were designed to play social games.”

Thus persuasion may be most effective when built on human interactions. Gay rights were probably advanced largely by the public’s growing awareness of friends and family members who were gay.

A corollary is that the most potent way to win over opponents is to accept that they have legitimate concerns, for that triggers an instinct to reciprocate. As it happens, we have a brilliant exemplar of this style of rhetoric in politics right now — Barack Obama.