By Christian Jarrett

Officially at least, last week’s global March for Science was politically neutral. However, there’s a massive over-representation of people with liberal, left-leaning views in science, and much of the science community is unhappy, to put it mildly, with the way politics is going, such as the Trump administration’s proposed deep cuts to science funding, and here in the UK, the impact of Brexit on British science.

Against the backdrop of these anxieties, many of the banners on display – such as “Alternative hypotheses, not alternative facts” and “Science reveals the truth” – conveyed a barely concealed message: if only right-wing conservatives could be a little more objective, less biased, more open-minded – you might say a little more “scientific” – then the world would be a better place.

Plenty of past psychology research lends some credence to this perspective: for instance conservatives tend to score lower on the trait of open-mindedness than liberals, and of course conservatives, more often than liberals, are sceptical toward the scientific consensus that human activity has had a significant impact on climate change. But it’s also easy to find psychological evidence of liberals’ bias, and liberals too are often in denial of unwelcome scientific theory, such as evolutionary accounts of sex differences in behaviour.

Now two new articles, published at the Social Science Research Network (SSRN) and in the Journal of Experimental Social Psychology, respectively, provide further compelling evidence that liberals, as much as conservatives, are prone to partisan bias – that is, showing rapid, easy acceptance of evidence that supports their existing beliefs – and that they are just as motivated to avoid hearing viewpoints that differ from their own. Whether we’re liberal or conservative, a first step toward combating our political prejudices, the paper in SSRN concludes, is “to recognize our collective vulnerability to perceiving the world in ways that validate our political beliefs”.

That paper in SSRN is a meta-analysis that combined the results of 41 previous experimental studies into partisan bias, collectively involving over 12,000 participants self-categorized as either liberal or conservative.

Each of the included studies followed a similar format: participants rated the credibility of evidence, such as a survey, experiment or op-ed, which either supported or contradicted their existing beliefs, such as on gun ownership or affirmative action. By holding the quality of the evidence and methods the same, but altering whether it supposedly came up with data supporting or contradicting participants’ viewpoints, this kind of research is able to reveal partisan bias – that is, whether participants’ are less sceptical and discerning when confronted with evidence that backs their own views.

Looking at the combined data from all these studies, Peter Ditto at University of California, Irvine, and his colleagues, found that liberals were as prone to partisan bias as conservatives. What’s more, partisan bias on all sides was especially on display when participants were presented with scientific data, perhaps undermining the chants of the science march: that it might be easier to reach political consensus if we could all agree to just stick to the facts. As Ditto and his team put it, “the prognosis for eradicating partisan bias with harder data and better education does not seem particularly rosy.”

The other new paper, led by Jeremy Frimer at the University of Winnipeg, used five studies to test American and Canadian participants’ motivation to encounter viewpoints different from their own. For instance, the first study offered participants more money to read an essay that contradicted their own views on same-sex marriage. The researchers found that equally among liberals and conservatives, a majority of participants preferred to forego cash if that meant avoiding opposing views.

Other studies involving other topics, such as gun control, abortion and climate change, led to similar results: liberals as much as conservatives were disinclined to hear the perspective of the other side. And the reasons they gave were similar: they thought hearing opposing views would make them feel uncomfortable or angry and harm their relationship with the source of the opposing views.

“The result of this desire to avoid ideological incongruous views is that liberals and conservatives live in ideological information bubbles, and what could ultimately be a contest of ideas is being replaced by two, non-interacting monopolies,” Frimer and his colleagues concluded.

This new research has some short-comings and shouldn’t be seen as the last word. It’s obviously North-American centric, and it’s not clear how much the results would apply in other parts of the world. It’s also extremely difficult to separate the moral dimension from psychology research into politics: for instance, how to deal with the potential argument that avoiding exposure to some opinions actually is more justified than avoiding exposure to others?

So of course more careful research is required, into ways that liberals and conservatives are similar and different. But if these new studies help us recognise that we all, no matter our political colours, could work harder to be more open-minded of opposing viewpoints, then this is surely constructive. As Sean Blanda put it in a Medium essay last year “The other side is not dumb“; well, probably no more than your side anyway.

—At Least Bias Is Bipartisan: A Meta-Analytic Comparison of Partisan Bias in Liberals and Conservatives

—Liberals and conservatives are similarly motivated to avoid exposure to one another’s opinions

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest