Confirmatory bias, cognitive dissonance, emote control, and (unconscious) psychological defense from a basic psychological and neurological perspective relating to politics and people identified with/supporting their chosen party/candidate/side and resulting views of the "opposition", affection the "punishment-reward" circuit in the brain, like addicts looking for a "fix":
“A recent imaging study by psychologist Drew Westen and his colleagues at Emory University provides firm support for the existence of emotional reasoning. Just prior to the 2004 Bush-Kerry presidential elections, two groups of subjects were recruited – fifteen ardent Democrats and fifteen ardent Republicans. Each was presented with conflicting and seemingly damaging statements about their candidate, as well as about more neutral targets such as actor Tom Hanks (who, it appears, is a likable guy for people of all political persuasions). Unsurprisingly, when the participants were asked to draw a logical conclusion about a candidate from the other – “wrong” – political party, the participants found a way to arrive at a conclusion that made the candidate look bad, even though logic should have mitigated the particular circumstances and allowed them to reach a different conclusion. Here’s where it gets interesting.
When this “emote control” began to occur, parts of the brain normally involved in reasoning were not activated. Instead, a constellation of activations occurred in the same areas of the brain where punishment, pain, and negative emotions are experienced (that is, in the left insula, lateral frontal cortex, and ventromedial prefrontal cortex). Once a way was found to ignore information that could not be rationally discounted, the neural punishment areas turned off, and the participant received a blast of activation in the circuits involving rewards – akin to the high an addict receives when getting his fix.
In essence, the participants were not about to let facts get in the way of their hot-button decision making and quick buzz of reward. “None of the circuits involved in conscious reasoning were particularly engaged,” says Westen. “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.”
Ultimately, Westen and his colleagues believe that “emotionally biased reasoning leads to the ‘stamping in’ or reinforcement of a defensive belief, associationg the participant’s ‘revisionist’ account of the data with positive emotion or relief and elimination of distress. ‘The result is that partisan beliefs are calcified, and the person can learn very little from new data,'” Westen says. Westen’s remarkable study showed that neural information processing related to what he terms “motivated reasoning” … appears to be qualitatively different from reasoning when a person has no strong emotional stake in the conclusions to be reached.
The study is thus the first to describe the neural processes that underlie political judgment and decision making, as well as to describe processes involving emote control, psychological defense, confirmatory bias, and some forms of cognitive dissonance.”
~ from “Evil Genes” by Barbara Oakley