“As the experiment was designed, the groups consisted of 'liberal' and 'conservative' members — the former from Boulder, the latter from Colorado Springs. It is widely known that Boulder tends to be liberal and that Colorado Springs tends to be conservative. The groups were screened to ensure that their members conformed to these stereotypes. In the parlance of election years, there were five 'blue state' groups and five 'red state' groups— five groups whose members initially tended toward liberal positions on the three issues, and five whose members tended toward conservative positions on those issues. People were asked to state their opinions anonymously both before and after fifteen minutes of group discussion, and also to try to reach a public verdict before the final anonymous statement. What was the effect of discussion? In almost every group, members ended up with more extreme positions after they spoke with one another. Discussion made civil unions more popular among liberals; discussion made civil unions less popular among conservatives. Liberals favored an international treaty to control global warming before discussion; they favored it more strongly after discussion. Conservatives were neutral on that treaty before discussion; they strongly opposed it after discussion. Mildly favorable toward affirmative action before discussion, liberals became strongly favorable toward affirmative action after discussion. Firmly negative about affirmative action before discussion, conservatives became even more negative about affirmative action after discussion. Aside from increasing extremism, the experiment also had an independent effect: it made both liberal groups and conservative groups significantly more homogeneous— and thus squelched diversity. Before members started to talk, many groups displayed a fair bit of internal disagreement. The disagreements were reduced as a result of a mere fifteen-minute discussion. Even in their anonymous statements, group members showed far more consensus after discussion than before. It follows that discussion helped to widen the rift between liberals and conservatives on all three issues. Before discussion, some liberal groups were, on some issues, fairly close to some conservative groups. The result of discussion was to divide them far more sharply.”