Red brains vs. blue brains

In a country sometimes fraught with tension between red states and blue states, neuroscience is suggesting an even deeper divide: red brains and blue ones.

Liberals and conservatives use a key part of the brain differently when confronted with snap decisions that involve overriding a habit, according to a study published Sunday in Nature Neuroscience.

The finding adds new support to an old theory that our political views spring partly from how our brains work.

"Political attitudes are dispositional in nature, almost more like personalities. They're not necessarily a choice," said the study's lead author David Amodio, a professor of psychology at New York University.

On top of that, political attitudes seem correlated with certain skills and behaviors.

Liberals were better at the kind of decision making that Amodio and his co-authors measured, leaving him anxious to point out in an interview that perhaps conservatives excel at other things.

"I tried to write this paper in a very politically agnostic way," he said, adding that he wished reporters would quit asking whether he's liberal or conservative. When pressed, he calls himself "an open-minded political moderate."

In California's capital, political operatives told of Amodio's research were quick to have fun with it.

"I could see where liberals would need that skill -- to recognize that they've got to get out of a situation quicker -- because personality-wise they do tend to be more rash," said Ray McNally, a Republican political consultant. That "increases the likelihood that you'll get into a situation that you need to get out of quickly. Otherwise, you'll have your head handed to you."

Or there's Democratic political consultant Roger Salazar: "A lot of folks on the liberal side are going to say yeah, that sounds right. Folks on the conservative side are going to go nuts. ... Conservatives will have a problem saying that's the way they're wired. They believe they come to their viewpoint because they're right and everyone else is wrong."

43 students were in study

For his part, Amodio cautioned that he studied 43 college students in California and New York and relied on their own descriptions along a continuum of how liberal or conservative they were. So no one should assume his results would apply to college students in Texas, let alone older adults anywhere.

Amodio and his colleagues fitted each student with a special cap that measures electrical activity in their brains. The team was looking for what happened in the anterior cingulate cortex, a part of the brain below the center of the forehead that regulates "conflict monitoring."

Conflict monitoring helps people know when to reject habit and try something else. We all use it constantly. We may be driving a familiar route without thinking much about it, and then come to a detour sign. It is conflict monitoring, in the anterior cingulate cortex, that alerts us to pay more attention to what we do next.

To simulate that complex reaction in a lab, researchers asked the students to make hundreds of rapid-fire decisions. Sitting in front of a computer terminal, the students were told to press a button if they saw one letter flash on the screen for a tenth of a second, but not if they saw another.

They were shown a series of M's and W's, and almost all the time -- 400 times out of 500 -- they saw the letter that required them to press the button. The other 100 times, they saw the other letter, and were supposed to hold off. Each time, they had four-tenths of a second to react.

"It's fast. It's too quick for you to think consciously about what you're doing," Amodio said. "It needs to be hard enough that people make a lot of errors," because the errors are the most interesting thing to study.

In the 400 easy trials, just about everyone got it right.

But in the 100 tough trials, when students saw the letter that meant they shouldn't press a button, self-described conservatives pressed the button anyway nearly half the time -- an error rate of 44 out of 100.

About the writer:

• The Bee's Carrie Peyton Dahlberg can be reached at (916) 321-1086 or cpeytondahlberg@sacbee.com.