political divides begin in the brain

NewScientist | JOHN HIBBING used to be a traditional political scientist. He studied elections, ran opinion polls and researched why some politicians opt to retire rather than wait around to be defeated by challengers. "About as traditional as it gets," he says.

Roughly a decade ago, though, Hibbing shifted to a new approach that is starting to revolutionise how we think about politics. He began to explore whether political preferences might be partly based in biology. The idea initially met with great scepticism from his peers. But Hibbing and his collaborators at the Political Physiology Lab at the University of Nebraska-Lincoln now have a stack of scientific publications backing the idea.

For example, when they measure the physical reactions of liberals and conservatives to aversive stimuli, they find major differences. Tough-on-crime, pro-military conservatives have a more pronounced startle reflex after hearing a sudden loud noise. They also show stronger skin responses when shown threatening images and look at them more rapidly and for longer.

It is conventional to think about political ideology as a set of ideas people consciously hold about the way society should be ordered. A tacit assumption is that we come to these beliefs rationally, by reading and thinking about the issues. If we differ, it is because we reason to different conclusions.

Hibbing's results suggest otherwise. "One of the things we're trying to get people to realise is that those who disagree with them politically really do experience the world in a different fashion," he says.

Many other seemingly apolitical differences between liberals and conservatives have also been discovered. For example, they tend to organise their living spaces differently, with conservatives favouring tidiness and conventionality, and liberals more tolerant of clutter. They also seem to have different art preferences and even senses of humour.

Most recently, and controversially, focus has shifted to differences in brain structures and functions. In one experiment, conservatives on average had a larger right amygdala, a region of the brain that processes responses to fear and threat. Liberals, in contrast, had more grey matter in the anterior cingulate cortex, an error-detecting region that is thought to be involved in causing us to stop repeated patterns of behaviour and change course.