Political partisans (or at the least the male ones who were the subject of this study) don't use their brain when talking about politics:
During the study, the partisans were given 18 sets of stimuli, six each regarding President George W. Bush, his challenger, Senator John Kerry, and politically neutral male control figures such as actor Tom Hanks. For each set of stimuli, partisans first read a statement from the target (Bush or Kerry). The first statement was followed by a second statement that documented a clear contradiction between the target's words and deeds, generally suggesting that the candidate was dishonest or pandering.and then
While reasoning about apparent contradictions for their own candidate, partisans showed activations throughout the orbital frontal cortex, indicating emotional processing and presumably emotion regulation strategies. There also were activations in areas of the brain associated with the experience of unpleasant emotions, the processing of emotion and conflict, and judgments of forgiveness and moral accountability.This is why I find partisanship so boring, and a lot of political blogging (particularly in New Zealand where there are much fewer non-partisan) so dull. To quote Billy Bragg: "And there's only two teams in this town/And you must follow one or the other/Let us win, let them lose, not the other way round." That's not what politics is about for me, there's no-one, particularly not anyone in power, who I care enough about to defend the indefensible.
Notably absent were any increases in activation of the dorsolateral prefrontal cortex, the part of the brain most associated with reasoning (as well as conscious efforts to suppress emotion).