“Experimental result: People held more extreme positions after they spoke with like-minded others. Liberals favored an international treaty to control global warming before discussion; they favored it far more strongly after discussion. Conservatives were neutral on that treaty before discussion, but they strongly opposed it after discussion.

The creation of enclaves of like-minded people also squelched diversity. Before people started to talk, many groups displayed a fair amount of internal disagreement on the three issues. The disagreements were greatly reduced as a result of a mere 15-minute discussion.