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Think your political beliefs arise from logic and reason? Think again. Some scientists found that they could tell who leaned left and who leaned right based on how their brains responded to disgusting pictures.

The findings, published in Current Biology, show that the brains of liberals and conservatives may by wired differently — and shed light on the biological factors at play in political beliefs.

Biology and politics have long been seen by many researchers as two separate realms. Some argue that biology is irrelevant to political questions, or that the links between the two are murky or oversimplified.

“Despite growing evidence from various fields, including genetics, cognitive neuroscience and psychology, many political scientists remain skeptical of research connecting biological factors with political ideology,” the study authors wrote.

But many of the same subjects at issue in certain political ideologies — attitudes toward sex, family, education and personal autonomy, for example — have an emotional component as much as a logic-based one. And some research has indicated political leanings can be inherited, much in the same way that height can inherited but modified, affected by a number of factors from nutrition to the environment.

To investigate this question, an international team led by Virginia Tech professor Read Montague called upon 83 volunteers, who took a test to determine what their political leanings were. Then, while sitting in a functional magnetic resonance imaging (MRI) machine — a brain scanner — the volunteers looked at 80 different images: 20 each of disgusting, threatening, pleasant or neutral images. The researchers watched how participants’ brains reacted to each of those images while in the machine. Later, participants were asked to rate how disgusting, pleasant or threatening each image was.

When shown a disgusting image — particularly one of a mutilated animal body — the conservatives’ brains reacted more strongly, and in different ways, compared with the liberals’ brains.

Montague told Cell Press: “A single disgusting image was sufficient to predict each subject’s political orientation” with 94 percent accuracy. “I haven’t seen such clean predictive results in any other functional-imaging experiments in our lab or others.”

Why this is remains unknown.

In the Current Biology article, Montague and colleagues from University College London, Rice University, the University of Nebraska, Lincoln, and Yale University wrote: “Although our results suggest that disgusting pictures evoke very different emotional processing in conservatives and liberals, it will take a range of targeted studies in the future to tease apart the separate contribution of each brain circuit.”

The difference between the two groups was stark despite the fact that the neural responses didn’t match the conscious ratings that participants gave those pictures.

Other images, whether threatening or pleasant or neutral, didn’t show the same link.

“People tend to think that their political views are purely cognitive (i.e., rational),” the study authors wrote. “However, our results further support the notion that emotional processes are tightly coupled to complex and high-dimensional human belief systems …”

Certainly politics is more than a few (possibly subconscious) emotional reactions; life history and experience also affect political beliefs, the study authors wrote. But it does raise some questions about whether partisans will need to develop new strategies to reach across the political aisle.

The take-away message for Election Day?

“Think, don’t just react,” Montague told a Virginia Tech publication. “But no one needs neuroscience to know that’s a good idea.”