Think your political beliefs arise from logic and reason? Think again. A team of scientists who studied the brains of liberal, moderate and conservative people found that they could tell who leaned left and 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 indeed 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 very separate realms. Some argue that biology is irrelevant to political questions, or that the links between the two are murky or oversimplified.

But many of the same subjects at issue in certain political ideologies – attitudes toward sex, family, education and personal autonomy – have an emotional component as much as a logic-based one. And some research has indicated that political leanings can be inherited.

To probe this controversial question, a team led by Virginia Tech scientists called upon 83 volunteers who took a test to determine what their political leanings were. Then, while sitting in the fMRI machine, they looked at 80 different images – 20 each of disgusting, threatening, pleasant or neutral images. The researchers watched how the participants’ brains reacted to each of those images while in the machine. Later, they 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.

The difference between the two groups was stark in spite of the fact that these 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, but it’s possible that pictures of threats don’t register the same way a real threat would, the authors pointed out.