Emory University psychologist Drew Westen put self-identified Democratic and Republican partisans in brain scanners and asked them to evaluate negative information about various candidates. Both groups were quick to spot inconsistency and hypocrisy -- but only in candidates they opposed.
When presented with negative information about the candidates they liked, partisans of all stripes found ways to discount it, Westen said. When the unpalatable information was rejected, furthermore, the brain scans showed that volunteers gave themselves feel-good pats -- the scans showed that "reward centers" in volunteers' brains were activated. The psychologist observed that the way these subjects dealt with unwelcome information had curious parallels with drug addiction as addicts also reward themselves for wrong-headed behavior.
Now this is damn interesting...