Liberal or Conservative? How Your Brain Reacts to Disgusting Images Reveals Your Political Affiliation

Laszlo Balogh/Reuters

Conservatives and liberals really are wired differently. Scientists can accurately predict whether a subject is left-wing tree-hugger or a right-wing gun-toter based on how their brains respond to certain images, a new study in Current Biology has found.

P. Read Montague, a scientist at Virginia Tech, said his experiment was inspired by data that shows political affiliation, like height, can be inherited. "I the same sense that height is highly genetically specified, it's also true that it's not predetermined by genetics; nutrition, sleep, starvation, dramatic physical injury, and so on can serve to change one's ultimate height. However, tall people have tall children, and this is a kind of starting point [for the experiement]," he said.

Montague and his colleagues asked subjects to look at positive, negative, and disgusting images and examined functional magnetic resonance images (fMRI) of their brains. His team found that conservatives' and liberals' brains behave differently when confronted with disgusting imagery. "Disgusting images, and the mutilated body of an animal especially, generated neural responses that were highly predictive of political orientation. That was true even though the neural predictors didn't necessarily agree with participants' conscious rating of those disturbing pictures," the authors of the study said.

The test proved surprisingly accurate. "A single disgusting image was sufficient to predict each subject's political orientation," Montague said. "I haven't seen such clean predictive results in any other functional imaging experiments in our lab or others."

What the study doesn't tell us is how conservative and liberal brains differ in their response to disgusting images. Do conservatives feel revulsion, and liberals pity? We don't know. "The results do not provide a simple bromide, but they do suggest that important foundational parts of political attitudes ride on top of preestablished neural responses that may have served to defend our forebears against environmental threats," Montague said.

However, he does think that if we better understand people's ideological responses, it could change the way we do politics. "If we can begin to see that some 'knee-jerk' reactions to political issues may be simply that—reactions—then we might take the temperature down a bit in the current boiler of political discourse."