Red state, blue state: fMRI predicts party ID

Liberals and conservatives use different parts of the brain when assessing risks, and activity in these regions can be used to predict political party identification, according to a study published Feb. 13 in PLOS ONE.

The predictive ability of this difference in brain activity, identified using functional imaging, is stronger than the long-standing model of using the political affiliation of parents to predict party choice in their children, according to Darren Schreiber, PhD, of the University of Exeter, U.K., and colleagues.

“These results suggest that liberals and conservatives engage different cognitive processes when they think about risk, and they support recent evidence that conservatives show greater sensitivity to threatening stimuli,” wrote the authors.

Schreiber and colleagues analyzed the brain activity of 82 study participants while they performed a gambling task. All subjects underwent neuroimaging on either a 1.5T or 3T MRI scanner, and political party registration available in public records was matched to each participant.

Republicans and Democrats did not differ in the risks they took, but there were differences in brain activity while the participants conducted the risk-taking task, reported the authors. Democrats showed significantly greater activity in the left insula, a region associated with social and self-awareness. Meanwhile Republicans showed significantly greater activity in the right amygdala, a region involved in the body's fight-or-flight system.

Brain activity in these two regions alone predicted whether a person is a Democrat or Republican with 82.9 percent accuracy, according to Schreiber and colleagues. This compares with 69.5 percent accuracy for the parental affiliation model.

What remains to be determined is the direction of causality, according to the authors. Differing genetic foundations and brain structures could influence ideology, or environmental factors and changes in cognitive function could lead to the changes in brain structure.

“Although genetic variation has been shown to contribute to variation in political ideology and strength of partisanship, the portion of the variance in political affiliation explained by activity in the amygdala and insula is significantly larger, suggesting that acting as a partisan in a partisan environment may alter the brain, above and beyond the effect of the heredity,” wrote Schreiber and colleagues.