BLUE STATE, red state. Big government, big business. Gay rights, fetal rights. The United States is riven by the politics of extremes. To paraphrase humor columnist Dave Barry, Republicans think of Democrats as godless, unpatriotic, Volvo-driving, France-loving, elitist latte guzzlers, whereas Democrats dismiss Republicans as ignorant, NASCAR-obsessed, gun-fondling religious fanatics. An exaggeration, for sure, but the reality is still pretty stark. Congress is in a perpetual stalemate because of the two parties' inability to find middle ground on practically anything.

According to the experts who study political leanings, liberals and conservatives do not just see things differently. They are differentin their personalities and even their unconscious reactions to the world around them. For example, in a study published in January, a team led by psychologist Michael Dodd and political scientist John Hibbing of the University of NebraskaLincoln found that when viewing a collage of photographs, conservatives' eyes unconsciously lingered 15 percent longer on repellent images, such as car wrecks and excrementsuggesting that conservatives are more attuned than liberals to assessing potential threats.

Meanwhile examining the contents of 76 college students' bedrooms, as one group did in a 2008 study, revealed that conservatives possessed more cleaning and organizational items, such as ironing boards and calendars, confirmation that they are orderly and self-disciplined. Liberals owned more books and travel-related memorabilia, which conforms with previous research suggesting that they are open and novelty-seeking.

These are not superficial differences. They are psychologically deep, says psychologist John Jost of New York University, a co-author of the bedroom study. My hunch is that the capacity to organize the political world into left or right may be a part of human nature.

Although conservatives and liberals are fundamentally different, hints are emerging about how to bring them togetheror at least help them coexist. In his recent book The Righteous Mind, psychologist Jonathan Haidt of the N.Y.U. Stern School of Business argues that liberals and conservatives need not revile one another as immoral on issues such as birth control, gay marriage or health care reform. Even if these two worldviews clash, they are equally grounded in ethics, he writes. Meanwhile studies by Jost and others suggest that political views reside on a continuum that is mediated in part by universal human emotions such as fear. Under certain circumstances, everyone can shift closer to the middleor drift further apart.

The Fear Factor

Psychologists have found that conservatives are fundamentally more anxious than liberals, which may be why they typically desire stability, structure and clear answers even to complicated questions. Conservatism, apparently, helps to protect people against some of the natural difficulties of living, says social psychologist Paul Nail of the University of Central Arkansas. The fact is we don't live in a completely safe world. Things can and do go wrong. But if I can impose this order on it by my worldview, I can keep my anxiety to a manageable level.

Anxiety is an emotion that waxes and wanes in all of us, and as it swings up or down our political views can shift in its wake. When people feel safe and secure, they become more liberal; when they feel threatened, they become more conservative. Research conducted by Nail and his colleague in the weeks after September 11, 2001, showed that people of all political persuasions became more conservative in the wake of the terrorist attacks. Meanwhile, in an upcoming study, a team led by Yale University psychologist Jaime Napier found that asking Republicans to imagine that they possessed superpowers and were impermeable to injury made them more liberal. There is some range within which people can be moved, Jost says.

More practically, instead of trying to change people's emotional state (an effect that is temporary), astute policy makers might be able to phrase their ideas in a way that appeals to different worldviews. In a 2010 paper Irina Feygina, a social psychology doctoral student at N.Y.U. who works with Jost, found a way to bring conservatives and liberals together on global warming. She and her colleagues wondered whether the impulse to defend the status quo might be driving the conservative pooh-poohing of environmental issues.

In an ingenious experiment, the psychologists reframed climate change not as a challenge to government and industry but as a threat to the American way of life. After reading a passage that couched environmental action as patriotic, study participants who displayed traits typical of conservatives were much more likely to sign petitions about preventing oil spills and protecting the Arctic National Wildlife Refuge.

Environmentalism may be an ideal place to find common political ground. Conservatives who are religious have this mind-set about being good stewards of the earth, to protect God's creation, and that is very compatible with green energy and conservation and other ideas that are usually classified as liberal, Nail says.

Moral Scorecards

On topics where liberals and conservatives will never see eye to eye, opposing sides can try to cultivate mutual respect. In The Righteous Mind, Haidt identifies several areas of morality. Liberals, he says, tend to value two of them: caring for people who are vulnerable and fairness, which for liberals tends to mean sharing resources equally. Conservatives care about those things, too, but for them fairness means proportionalitythat people should get what they deserve based on the amount of effort they have put in. Conservatives also emphasize loyalty and authority>, values helpful for maintaining a stable society.

In a 2009 study Haidt and two of his colleagues presented more than 8,000 people with a series of hypothetical actions. Among them: kick a dog in the head; discard a box of ballots to help your candidate win; publicly bet against a favorite sports team; curse your parents to their faces; and receive a blood transfusion from a child molester. Participants had to say whether they would do these deeds for money and, if so, for how much$10? $1,000? $100,000? More? Liberals were reluctant to harm a living thing or act unfairly, even for $1 million, but they were willing to betray group loyalty, disrespect authority or do something disgusting, such as eating their own dog after it dies, for cash. Conservatives said they were less willing to compromise on any of the moral categories.

Haidt has a message for both sides. He wants the left to acknowledge that the right's emphasis on laws, institutions, customs and religion is valuable. Conservatives recognize that democracy is a huge achievement and that maintaining the social order requires imposing constraints on people. Liberal values, on the other hand, also serve important roles: ensuring that the rights of weaker members of society are respected; limiting the harmful effects, such as pollution, that corporations sometimes pass on to others; and fostering innovation by supporting diverse ideas and ways of life.

Haidt is not out to change people's deepest moral beliefs. Yet he thinks that if people could see that those they disagree with are not immoral but simply emphasizing different moral principles, some of the antagonism would subside. Intriguingly, Haidt himself has morphed from liberal to centrist over the course of his research. He now finds value in conservative tenets that he used to reject reflexively: It's yin and yang. Both sides see different threats; both sides are wise to different virtues.