How the brain responds to disgusting images could reveal whether an individual is liberal or conservative.
Researchers looked at functional magnetic resonance imaging (MRI) brain scans that were taken while participants looked at stomach-churning images such as dirty toilets or gore, mixed with more pleasant pictures, Virginia Tech Carilion Research Institute reported.
"Disgusting images generate neural responses that are highly predictive of political orientation even when those neural responses don't correspond with an individual's conscious reaction to the images," said Read Montague, a Virginia Tech Carilion Research Institute professor who led the study. "Remarkably, we found that the brain's response to a single disgusting image was enough to predict an individual's political ideology."
After the brain scans the participants were asked to answer questions about their political ideology and give their response to hot-button issues such as gay marriage. They found responses to the images could predict how a person would respond to political issues with between 95 and 98 percent accuracy.
The findings suggest political ideologies are mapped onto established neural responses, which may have helped our ancestors protect themselves against environmental threats. These responses could also be passed down through family lines.
"We pursued this research because previous work in a twin registry showed that political ideology - literally the degree to which someone is liberal or conservative - was highly heritable, almost as heritable as height," Montague said.
Just as sleeping habits and nutrition can influence someone's height, environmental factors can also influence one's political instincts.
"People can deny their biological instincts for an idea - think of hunger strikes for political reasons," Montague said. "That requires a high degree of cognitive control, and that's the point."
The Wellcome Trust Principal Research Fellowship, the Gatsby Charitable Trust, the National Science Foundation, and the Kane Family Foundation supported the research.
