Brain Scans and Politics

"We did not see any increased activation of the parts of the brain normally engaged during reasoning," Westen is quoted as saying in an Emory University press release. "What we saw instead was a network of emotion circuits lighting up ... Essentially, it appears as if partisans twirl the cognitive kaleidoscope until they get the conclusions they want, and then they get massively reinforced for it, with the elimination of negative emotional states and activation of positive ones," Westen said.

An article about confirmation bias in politically interested people in _Scientific American_.