Preaching to the choir

Fairly obvious, but folks who saw Farenheit 9/11 or listen to Rush tend to already support what is being preached.

The study, which has a margin of error of 5 percentage points, found that about 8 percent of those polled had watched Moore's movie, which takes aim at the president. Seven percent said they had listened to Limbaugh - a Bush backer - within the last week.

While the two audiences were similar in size, their worldviews were diametrically opposed. Eighty-six percent of Moore moviegoers said they disapproved of the president's job performance. Among Limbaugh's listeners, 88 percent approved of the job Bush is doing.

The study found that the politically inclined are seeking information that simply reinforces their views. That tendency is a "natural human phenomenon" and a predictable finding, Jamieson said.