Political bias affects brain activity, study finds

Democrats and Republicans both adept at ignoring facts, brain scans show


Democrats and Republicans alike are adept at making decisions without letting the facts get in the way, a new study shows.

And they get quite a rush from ignoring information that’s contrary to their point of view.

asked staunch party members from both sides to evaluate information
that threatened their preferred candidate prior to the 2004
Presidential election. The subjects’ brains were monitored while they

The results were announced today.

did not see any increased activation of the parts of the brain normally
engaged during reasoning,” said Drew Westen, director of clinical
psychology at Emory University. “What we saw instead was a network of
emotion circuits lighting up, including circuits hypothesized to be
involved in regulating emotion, and circuits known to be involved in
resolving conflicts.”

Bias on both sides
test subjects on both sides of the political aisle reached totally
biased conclusions by ignoring information that could not rationally be
discounted, Westen and his colleagues say.

with their minds made up, brain activity ceased in the areas that deal
with negative emotions such as disgust. But activity spiked in the
circuits involved in reward, a response similar to what addicts
experience when they get a fix, Westen explained.

The study points to a total lack of reason in political decision-making.

of the circuits involved in conscious reasoning were particularly
engaged,” Westen said. “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.”

absent were any increases in activation of the dorsolateral prefrontal
cortex, the part of the brain most associated with reasoning.

tests involved pairs of statements by the candidates, President George
W. Bush and Senator John Kerry, that clearly contradicted each other.
The test subjects were asked to consider and rate the discrepancy. Then
they were presented with another statement that might explain away the
contradiction. The scenario was repeated several times for each

brain-scan technique known as functional magnetic resonance imaging, or
fMRI, revealed a consistent pattern. Both Republicans and Democrats
consistently denied obvious contradictions for their own candidate but
detected contradictions in the opposing candidate.

“The result is that partisan beliefs are calcified, and the person can learn very little from new data,” Westen said.

relatively neutral candidates were introduced into the mix, such as the
actor Tom Hanks. Importantly, both the Democrats and Republicans
reacted to the contradictions of these characters in the same manner.

The findings could prove useful beyond the campaign trail.

from executives and judges to scientists and politicians may reason to
emotionally biased judgments when they have a vested interest in how to
interpret ‘the facts,'” Westen said.

The researchers will present the findings Saturday at the Annual Conference of the Society for Personality and Social Psychology