Exploring the neurobiology of politics, scientists have found that liberals tolerate ambiguity and conflict better than conservatives because of how their brains work.
Scientists at New York University and the University of California, Los Angeles showed through a simple experiment to be reported today in the journal Nature Neuroscience 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 showed "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." Scientists instructed them 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 their 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. Liberals and conservatives were equally accurate in recognizing M.
Researchers obtained the same results when they repeated the experiment in reverse, asking another set of participants to tap when they saw W.
Frank J. Sulloway, a researcher at the Institute of Personality and Social Research, at the University of California, Berkeley, who was not involved in the study, said results "provided an elegant demonstration that individual differences on a conservative-liberal dimension are strongly related to brain activity."
Analyzing the data, Sulloway said liberals were 4.9 times more likely than conservatives to show activity in the brain circuits that deal with conflicts and were 2.2 times more likely to score in the top half of the distribution for accuracy.
Based on the results, Sulloway said, liberals could be expected to more readily accept new social, scientific or religious ideas.
"There is ample data from the history of science showing that social and political liberals indeed do tend to support major revolutions in science," said Sulloway, who has written about the history of science and has studied behavioral differences between conservatives and liberals.
Lead author David Amodio, an assistant professor of psychology at New York University, cautioned that the study looked at a narrow range of human behavior and it would be a mistake to conclude that one political orientation was better than another. The tendency of conservatives to block distracting information could be a good thing depending on the situation, he said.
Political orientation, he noted, occurs along a spectrum, and positions on specific issues, such as taxes, are influenced by many factors, including education and wealth. Some liberals oppose higher taxes, and some conservatives support abortion.
Still, he acknowledged that a meeting of the minds between conservatives and liberals looked difficult given the study results.
"Does this mean liberals and conservatives are never going to agree? Maybe it suggests one reason why they tend not to get along," Amodio said.
Denise Gellene writes for the Los Angeles Times.