How you react to a disgusting image can give hints on your political leaning. Earlier studies have shown that individuals who identify themselves as politically conservative tend to have involuntary physiological responses to disgusting images such as animal remains, bodily waste and gore.
Now, a group of researchers gives credence to these earlier studies with their new findings that liberals and conservatives experience different brain activities when they look at disgusting images.
Read Montague from Virginia Tech Carilion Research Institute and colleagues recruited 83 individuals who were asked to look at 80 images. Some of the images were pleasant, depicting babies and landscapes, while others were neutral and disgusting, such as those that show mutilated carcasses and dirty toilets.
The researchers performed fMRI brain scans on the participants as they looked at the series of varying images, and asked them to rate the images according to their emotional impact. The researchers also asked the participants to complete a questionnaire, which included items that asked them whether or not they agree with hotly debated issues, such as gay marriage as well as how often they talk about politics, so as to determine if a participant is conservative, moderate, or liberal.
Although conservatives and liberals reported having similar emotional reactions to the images, how their brains reacted to the disgusting images differed significantly.
Based on the results of the brain scans, the researchers found that conservatives tend to react more strongly to disgusting images, having increased activity in regions of their brain that are involved in processing disgust and regulating emotion. The liberals, on the other hand, had increased activity in different brain regions.
"Disgusting images, especially those related to animal-reminder disgust (e.g., mutilated body), generate neural responses that are highly predictive of political orientation even though these neural predictors do not agree with participants' conscious rating of the stimuli," Montague and colleagues wrote.
The researchers said that a person's response to disgusting images could predict with high accuracy his or her political orientation.
"In fact, the responses in the brain are so strong that we can predict with 95 percent accuracy where you'll fall on the liberal-conservative spectrum by showing you just one picture," Montague said. "This was surprising as there are no other reports where people's response to just one stimulus predicts anything behaviorally interesting."
The study was profiled in the journal Biology on Oct. 30.