I’m very much enjoying Michael Shermer’s new book The Believing Brain. It’s about how the brain forms beliefs, why people hold on to their beliefs so strongly, and why people believe in weird things like ghosts and conspiracy theories.
On p. 260, Shermer quotes from a study (pdf) by Drew Westen, et al, where his team ran fMRI scans on the brains of political partisans to see what parts of their brains were firing when engaged in political dispute:
We did not see any increased activation of the parts of the brain normally engaged during reasoning. What we saw instead was a network of emotion circuits lighting up… Essentially, it appears as if partisans twirl the cognitive kaleidascope 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.
There you have it: scientific proof that partisans aren’t quite right in the head.