When like-minded people sit down and talk things out, they become more like-minded and less tolerant.

That’s what David Schkade (University of California–San Diego), Cass Sunstein (University of Chicago), and Reid Hastie (University of Chicago) found out when they conducted a seemingly innocuous experiment in Colorado:

“Groups [of five members each] from Boulder, a predominantly liberal city, met and discussed global warming, affirmative action, and civil unions for same-sex couples; groups from Colorado Springs, a predominately conservative city, met to discuss the same issues. The major effect of deliberation was to make group members more extreme than they were when they started talk.” Conservatives became more conservative, liberals more liberal.

As people increasingly are able to sort themselves into places where they feel comfortable–both physically and virtually–this isn’t happy news. In the blogosphere, where physical and economic constraints are minimal, the most popular blogs seem to be the most partisan. How many people have both Michelle Malkin and Glenn Greenwald on their blogrolls?

Read all about it at “What Happened on Deliberation Day?” (PDF)