From the LA Times:
In a simple experiment reported today in the journal Nature Neuroscience, scientists at New York University and UCLA show that political orientation is related to differences in how the brain processes information.
Previous psychological studies have found that conservatives tend to be more structured and persistent in their judgments whereas liberals are more open to new experiences. The latest study found those traits are not confined to political situations but also influence everyday decisions.
The results show "there are two cognitive styles -- a liberal style and a conservative style," said UCLA neurologist Dr. Marco Iacoboni, who was not connected to the latest research.
Participants were college students whose politics ranged from "very liberal" to "very conservative." They were instructed to tap a keyboard when an M appeared on a computer monitor and to refrain from tapping when they saw a W.
M appeared four times more frequently than W, conditioning participants to press a key in knee-jerk fashion whenever they saw a letter.
Each participant was wired to an electroencephalograph that recorded activity in the anterior cingulate cortex, the part of the brain that detects conflicts between a habitual tendency (pressing a key) and a more appropriate response (not pressing the key). Liberals had more brain activity and made fewer mistakes than conservatives when they saw a W, researchers said.