Jonathan Haidt, the author of The Righteous Mind, is on a roll. A few months ago, Haidt and his collaborators released a study of the psychology of libertarianism, which I blogged about here. This week, they published a paper on what liberals and conservatives think about morality–and what they think about each other. Here are the key findings:

In reality, liberals endorse the individual-focused moral concerns of compassion and fairness more than conservatives do, and conservatives endorse the group-focused moral concerns of ingroup loyalty, respect for authorities and traditions, and physical/spiritual purity more than liberals do…Across the political spectrum, moral stereotypes about “typical” liberals and conservatives correctly reflected the direction of actual differences in foundation endorsement but exaggerated the magnitude of these differences. Contrary to common theories of stereotyping, the moral stereotypes were not simple underestimations of the political outgroup’s morality. Both liberals and conservatives exaggerated the ideological extremity of moral concerns for the ingroup as well as the outgroup. Liberals were least accurate about both groups.

As with the libertarianism study, some of these conclusions are not very surprising. Liberals emphasize compassion while conservatives are more concerned about authority and tradition. We already knew that, which is precisely what Haidt’s research documents.

The interesting result is that liberals are more likely than conservatives to exaggerate the differences between them. Liberals, after all, like to think of themselves as especially resistant to prejudice, even concerning their political opponents. At Mother Jones, Kevin Drum asks why liberals’ self-conception should be so distant from reality. He suggests four explanations:

One possibility is that the study is wrong. Its sample was light on extreme conservatives, and that might have made a difference even after the researchers corrected for it. A second possibility is that liberals are over-influenced by Fox News and Rush Limbaugh. We take them as representative of conservatives even though they represent only its right wing. A third possibility is that the conservative leadership in Washington DC is more hardnosed than the movement as a whole, and everyone legitimately takes that as representing real-world conservatism. And finally, a fourth possibility is simply that liberals are wrong. We interact very little with conservative institutions (churches, business groups, etc.) and therefore don’t understand them, while conservatives have no choice but to interact with liberal institutions (Hollywood, academia, etc.).

The fourth possibility has the most explanatory power. Although they pride themselves on being open-minded, liberals generally have far less contact with conservatives than conservatives do with liberals. As a result, their understanding of conservatives and conservatism is frequently a caricature. The problem is not simply that they disagree. It’s that they have little first-hand experience of whom or what they’re disagreeing with.

As Drum acknowledges explicitly, one cause of this ignorance is that liberals are unlikely to participate in institutions where conservatives have a substantial presence. Another, to which he only alludes, is liberal dominance of the entertainment industry (as opposed to the news and opinion business). Complaints about Hollywood are the stuff of cliché. But really: when was the last time you saw a movie that depicted conservatives, the traditionally religious, people who work in “brown” industries, or suburbanites favorably?

Yet Drum misses the last and perhaps most important cause of liberals’ alienation from conservatives: their tendency to cluster in major metropolitan areas. I’m unaware of any study of the geographical distribution of ideological self-identification as such. But it does appear that Democrats are far more likely than Republicans to live in uncompetitive House districts.

Contrary to the stereotype, then, it’s liberals who tend to live in politically-monolithic bubbles. Under those conditions, it’s no wonder that they take their cues from the only conservatives they’re likely to encounter, the windbags on talk radio and cable news. So in the spirit of civic friendship, I offer a message to liberals: you should get out more, whether physically or around the Internet. The water is warm, and you might be surprised by what you find.