Scientists use brain imaging to predict political ideology

Many people who are passionate about politics may claim they have nothing in common with people who are on the opposite side of the political spectrum — but could those differences extend to something as fundamental as brain activity? A study published in PNAS Nexus shows that differences in ideology can be observed through biological and neurological testing.

Politics is a complex and nuanced form of ideology that comprises many different ideas and opinions. Despite this, it is often boiled down to simply “left wing” or “right wing” with both sides frequently being contentious.

Previous research has studied what factors influence people to gravitate toward one political affiliation or another, as well as how political belief can affect attitude and behavior. This study seeks to expand on this body of research and better understand if these ideological differences extend into the brain itself, potentially showing biological differences.

Researcher Seo-Eun Yang and colleagues utilized brain imaging data from 174 young adults from Ohio State University. The sample was predominantly female and had a mean age of 21.4 years old. Participants underwent an hour and a half-long functional MRI comprising of 8 tasks.

“None of the eight tasks was designed to elicit partisan responses,” said Yang, an assistant professor of political science at Northeastern University, in a news release.

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Additionally, participants answered a series of self-report questions on demographics, their ideological position, and the ideological leanings their parents and hometown.

Results showed that the fMRI revealed noticeable and significant differences between liberal and conservative people. Tasks that measured empathy, reward, retrieval, and functional connectivity showed the strongest predictive power of political ideology.

The amygdala, inferior frontal gyrus, and hippocampus were related to political association. The empathy task was the only one of the tasks associated with moderate political beliefs, suggesting that political beliefs may be strongly related to one’s emotions.

“The results suggest that the biological and neurological roots of political behavior run much deeper than we previously thought,” said study co-author Skyler Cranmer, the Phillips and Henry Professor of Political Science at The Ohio State University.

“We looked at the brain as a complex system of regions interacting with each other to produce these behaviors. Most other studies have looked at one region of the brain in isolation to see how it was activated or not activated when they were subjected to political stimuli,” he added.

This study made strides into understanding how brain function relates to political affiliation. Regardless, this study has limitations to speak of. One such limitation is that the political affiliation of subjects skewed liberal, with a very limited number of extreme conservatives. Additionally, recruiting subjects from a university limits generalizability due to the subjects often having many similarities, such as age and education level.

“Although the direction of causality remains unclear—do people’s brains reflect the political orientation they choose or do they choose their political orientation because of their functional brain structure—the evidence here motivates further scrutiny and followup analyses into the biological and neurological roots of political behavior,” the researchers concluded.

The study, “Functional Connectivity Signatures of Political Ideology“, was authored by Seo Eun Yang, James D Wilson, Zhong-Lin Lu, and Skyler Cranmer.