Liberals and conservatives can become equally bug-eyed and irrational when talking politics, especially when they are on the defensive.
Using M.R.I. scanners, neuroscientists have now tracked what happens in the politically partisan brain when it tries to digest damning facts about favored candidates or criticisms of them. The process is almost entirely emotional and unconscious, the researchers report, and there are flares of activity in the brain's pleasure centers when unwelcome information is being rejected.
"Everything we know about cognition suggests that, when faced with a contradiction, we use the rational regions of our brain to think about it, but that was not the case here," said Dr. Drew Westen, a psychologist at Emory and lead author of the study, to be presented Saturday at meetings of the Society for Personality and Social Psychology in Palm Springs, Calif.
The results are the latest from brain imaging studies that provide a neural explanation for internal states, like infatuation or ambivalence, and a graphic trace of the brain's activity.
A recent study led by Dr. Drew Westen, a Professor of Psychology at Emory University in Atlanta, Georgia has concluded that political partisans use an "almost entirely emotional and unconscious" thought process when digesting damaging information about a favored political candidate.

The experiment used fMRI scans of 30 men who self-identified as either a committed Republican or Democrat.  The subjects were given a series of conflicting quotes by either President Bush or Senator Kerry, and covered such topics as the Enron scandal and the current state of Social Security.  The quotes were doctored to maximize the apparent contradiction, but were presented as factual.

The results suggests that many seemingly rational political decisions are strongly influenced by unconscious emotional reactions.  Such conclusions match well results from advertising psychology which say that purchases are also not as rational as people believe.  Past fMRI studies have found that Democrat and Republican partisans tend to experience different emotions when shown an image of a preferred candidate.

Westen will present his results next month at a meetings of the Society for Personality and Social Psychology in Palm Springs, CA.