Political divides begin in the brain

Differences in political belief seem to have some basis in biology, which could promote tolerance on both sides, but probably won't

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.

Results like these need to be treated with caution. They involve relatively small samples and it is far from clear whether your brain causes you to have a particular political outlook or vice versa - or some combination of both. Moreover, in these studies liberalism and conservatism are largely based on self-description, which introduces a fair amount of variability - especially as politically left and right are perhaps better thought of as a continuum than a binary choice.

Nevertheless, the amygdala finding dovetails nicely with Hibbing's work on startle reflexes. Conservatives on average really do seem to respond to fear and threat differently, and to focus on what Hibbing calls the "aversive" in life, rather than the "appetitive".

These experiments are themselves an extension of an older and long-standing body of research on personality differences between liberals and conservatives. Across a range of studies, liberals consistently rate higher on a trait called openness to experience. They are both ideologically liberal - comfortable with policy innovation and social and political change - and also personally liberal.

Conservatives, in contrast, tend to be less open and also consistently rate higher on conscientiousness, which means that they tend to prize orderliness and structure. Conscientious people are driven, competent, organised - and, on average, politically conservative.

Finally, there are a substantial number of genetic studies. Again and again, these show that identical twins (who share all of their DNA) tend to be far more politically similar to one another than fraternal twins (who share half of it). The studies suggest that 40 per cent or more of the variance in ideological views may ultimately be rooted in genes.

If all of this is true, it may reflect something we've always sort of known, but never really been willing to admit: liberals and conservatives are different sorts of people. Rational thinking about politics is not irrelevant, but seems to be less important than we thought. And this raises some important questions about how the new science of politics could be received and used.

Hibbing is devoted to the idea that his work ought to be used to promote greater political tolerance. "The notion that our opponents are not simply obstinate or uninformed but have this way of experiencing the world that we don't understand could be useful," he says.

As far as toleration goes, the research certainly suggests that liberals and conservatives alike have strengths and weaknesses, and ought to fare better in some situations than others. Liberals are better at handling nuance, uncertainty and flexibility, while conservatives do better with leadership, duty and loyalty. There are good things about both ideologies.

The problem with the tolerance approach, though, is that it requires the acceptance of contentious new science on both sides. How do we know that's going to occur? What's to say conservatives won't reject the growing body of science on our political differences - as is their wont - and defensively assume that this is all just a way of putting them down and calling them inferior even though it isn't? In that case, the research could prove divisive, not helpful.

Frankly, in light of the polarisation of everything else in the US, it's hard not to fear that outcome.

Chris Mooney's new book is The Republican Brain: The science of why they deny science - and reality (Wiley)

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