Most people are surprised to learn that there are real, stable differences in personality between conservatives and liberals—not just different views or values, but underlying differences in temperament.

Psychologists John Jost of New York University, Dana Carney of Harvard, and Sam Gosling of the University of Texas have demonstrated that conservatives and liberals boast markedly different home and office decor. Liberals are messier than conservatives, their rooms have more clutter and more color, and they tend to have more travel documents, maps of other countries, and flags from around the world. Conservatives are neater, and their rooms are cleaner, better organized, more brightly lit, and more conventional. Liberals have more books, and their books cover a greater variety of topics. And that’s just a start. Multiple studies find that liberals are more optimistic. Conservatives are more likely to be religious. Liberals are more likely to like classical music and jazz, conservatives, country music. Liberals are more likely to enjoy abstract art. Conservative men are more likely than liberal men to prefer conventional forms of entertainment like TV and talk radio. Liberal men like romantic comedies more than conservative men. Liberal women are more likely than conservative women to enjoy books, poetry, writing in a diary, acting, and playing musical instruments.

"All people are born alike—except Republicans and Democrats," quipped Groucho Marx, and in fact it turns out that personality differences between liberals and conservatives are evident in early childhood. In 1969, Berkeley professors Jack and Jeanne Block embarked on a study of childhood personality, asking nursery school teachers to rate children’s temperaments. They weren’t even thinking about political orientation.

Twenty years later, they decided to compare the subjects’ childhood personalities with their political preferences as adults. They found arresting patterns. As kids, liberals had developed close relationships with peers and were rated by their teachers as self-reliant, energetic, impulsive, and resilient. People who were conservative at age 23 had been described by their teachers as easily victimized, easily offended, indecisive, fearful, rigid, inhibited, and vulnerable at age 3. The reason for the difference, the Blocks hypothesized, was that insecure kids most needed the reassurance of tradition and authority, and they found it in conservative politics.

The most comprehensive review of personality and political orientation to date is a 2003 meta-analysis of 88 prior studies involving 22,000 participants. The researchers—John Jost of NYU, Arie Kruglanski of the University of Maryland, and Jack Glaser and Frank Sulloway of Berkeley—found that conservatives have a greater desire to reach a decision quickly and stick to it, and are higher on conscientiousness, which includes neatness, orderliness, duty, and rule-following. Liberals are higher on openness, which includes intellectual curiosity, excitement-seeking, novelty, creativity for its own sake, and a craving for stimulation like travel, color, art, music, and literature.

The study’s authors also concluded that conservatives have less tolerance for ambiguity, a trait they say is exemplified when George Bush says things like, "Look, my job isn’t to try to nuance. My job is to tell people what I think," and "I’m the decider." Those who think the world is highly dangerous and those with the greatest fear of death are the most likely to be conservative.

Liberals, on the other hand, are "more likely to see gray areas and reconcile seemingly conflicting information," says Jost. As a result, liberals like John Kerry, who see many sides to every issue, are portrayed as flip-floppers. "Whatever the cause, Bush and Kerry exemplify the cognitive styles we see in the research," says Jack Glaser, one of the study’s authors, "Bush in appearing more rigid in his thinking and intolerant of uncertainty and ambiguity, and Kerry in appearing more open to ambiguity and to considering alternative positions."

Jost’s meta-analysis sparked furious controversy. The House Republican Study Committee complained that the study’s authors had received federal funds. George Will satirized it in his Washington Post column, and The National Review called it the "Conservatives Are Crazy" study. Jost and his colleagues point to the study’s rigorous methodology. The study used political orientation as a dependent variable, meaning that where subjects fall on the political scale is computed from their own answers about whether they’re liberal or conservative. Psychologists then compare factors such as fear of death and openness to new experiences, and seek statistically significant correlations. The findings are quintessentially empirical and difficult to dismiss as false.

Yet critics retort that the research draws negative conclusions about conservatives while the researchers themselves are liberal. And it’s true that over the decades, a disproportionate amount of the research has focused on figuring out what’s behind conservative behavior. Right shift is likewise more studied than left shift, largely because most of that research has been since 9/11, and aimed at trying to explain the conservative conversions of people like Cinnamon Stillwell.

Even with impeccable methodology, bias may creep into the choice of which phenomena to study. "There is a bias among social scientists," admits Glaser. "They look for the variables that are unflattering. There probably are other nice personality traits associated with conservatism, but they haven’t shown up in the research because it’s not as well studied."

"There are differences between liberals and conservatives, and people can value them however they like," Jost points out. "There is nothing inherently good or bad about being high or low on the need for closure or structure. Some may see religiosity as a positive, whereas others may see it more neutrally, and so on."