The Biology of Partisanship

What with the Alito confirmation and the State of the Union Address, I thought it timely to point out a report released last week showing that both Democrats and Republicans are remarkably adept at ignoring facts that contradict their philosophies. The researchers, based at Emory University, monitored brain activity in members of both political parties while asking them to ponder information from the 2004 Presidential election that threatened their preferred candidate.

In short, brain circuits that control reasoning shut down, and circuits involved in emotional control and reward lit up. The pattern was consistent and, ironically, bipartisan - both Republicans and Democrats "consistently denied obvious contradictions for their own candidate but detected contradictions in the opposing candidate."

So what in the brain, biologically speaking, drives partisan preference? How do we choose one side and stick to it? And I'm not just talking about politics - Red Sox vs. Yankees, Mac vs. Windows, Coke vs. Pepsi, anything that involves a strong, unshakeable preference I imagine would fall under the same category. What has more influence, nature or nurture (yes, I have to open that can of worms)? Are Democrats more left brain, Republicans more right brain? (And are anarchists schizophrenic?)

[See Slashdot and LiveScience for more.]