Liberals and conservatives exhibit different cognitive styles and converging lines of evidence suggest that biology influences differences in their political attitudes and beliefs. In particular, a recent study of young adults suggests that liberals and conservatives have significantly different brain structure, with liberals showing increased gray matter volume in the anterior cingulate cortex, and conservatives showing increased gray matter volume in the in the amygdala. Here, we explore differences in brain function in liberals anconservatives by matching publicly-available voter records to 82 subjects who performed a risk-taking task during functional imaging. Although the risk-taking behavior of Democrats (liberals) and Republicans (conservatives) did not differ, their brain activity did. Democrats showed significantly greater activity in the left insula, while Republicans showed significantly greater activity in the right amygdala.
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.* These results suggest that liberals and conservatives engage different cognitive processes when they think about risk.
In fact, brain activity in these two regions alone can be used to predict whether a person is a Democrat or Republican with 82.9% accuracy. By comparison, the longstanding traditional model in political science, which uses the party affiliation of a person’s mother and father to predict the child’s affiliation, is only accurate about 69.5% of the time. And another model based on the differences in brain structure distinguishes liberal from conservatives with only 71.6% accuracy.
The model also outperforms models based on differences in genes. “Although genetics have been shown to contribute to differences in political ideology and strength of party politics, the portion of variation in political affiliation explained by activity in the amygdala and insula is significantly larger, suggesting that affiliating with a political party and engaging in a partisan environment may alter the brain, above and beyond the effect of heredity.” (Schreiber D, Fonzo G, Simmons AN, Dawes CT, Flagan T, et al. (2013) Red Brain, Blue Brain: Evaluative Processes Differ in Democrats and Republicans. PLoS ONE 8(2): e52970. doi:10.1371/journal.pone.0052970)