Science Confirms: Politics Wrecks Your Ability to Do Math
Farewell, Enlightenment: New research suggests that people even solve math problems differently if their political ideology is at stake.
—By Chris Mooney
| Wed Sep. 4, 2013 9:59 AM PDT
A new study finds that even how you solve a difficult math problem can depend on your politics.
Everybody knows that our political views can sometimes get in the way of thinking clearly. But perhaps we don't realize how bad the problem actually is. According to a new psychology paper, our political passions can even undermine our very basic reasoning skills. More specifically, the study finds that people who are otherwise very good at math may totally flunk a problem that they would otherwise probably be able to solve, simply because giving the right answer goes against their political beliefs.
The study, by Yale law professor Dan Kahan and his colleagues, has an ingenious design. At the outset, 1,111 study participants were asked about their political views and also asked a series of questions designed to gauge their "numeracy," that is, their mathematical reasoning ability. Participants were then asked to solve a fairly difficult problem that involved interpreting the results of a (fake) scientific study. But here was the trick: While the fake study data that they were supposed to assess remained the same, sometimes the study was described as measuring the effectiveness of a "new cream for treating skin rashes." But in other cases, the study was described as involving the effectiveness of "a law banning private citizens from carrying concealed handguns in public."
The result? Survey respondents performed wildly differently on what was in essence the same basic problem, simply depending upon whether they had been told that it involved guns or whether they had been told that it involved a new skin cream. What's more, it turns out that highly numerate liberals and conservatives were even more—not less—susceptible to letting politics skew their reasoning than were those with less mathematical ability.
But we're getting a little ahead of ourselves—to fully grasp the Enlightenment-destroying nature of these results, we first need to explore the tricky problem that the study presented in a little bit more detail.
Let's start with the "skin cream" version of this brain twister. You can peruse the image below to see exactly what research subjects read (and try out your own skill at solving it), or skip on for a brief explanation:
Full text of one version of the study's "skin cream" problem
As you can see above, the survey respondents were presented with a fictional study purporting to assess the effectiveness of a new skin cream, and informed at the outset that "new treatments often work but sometimes make rashes worse" and that "even when treatments don't work, skin rashes sometimes get better and sometimes get worse on their own." They were then presented with a table of experimental results, and asked whether the data showed that the new skin cream "is likely to make the skin condition better or worse."
So do the data suggest that the skin cream works? The correct answer in the scenario above is actually that patients who used the skin cream were "more likely to get worse than those who didn't." That's because the ratio of those who saw their rash improve to those whose rash got worse is roughly 3:1 in the "skin cream" group, but roughly 5:1 in the control group—which means that if you want your rash to get better, you are better off not using the skin cream at all. (For half of study subjects asked to solve the skin cream problem, the data were reversed and presented in such a way that they did actually suggest that the skin cream works.)
This is no easy problem for most people to solve: Across all conditions of the study, 59 percent of respondents got the answer wrong. That is, in significant part, because trying to intuit the right answer by quickly comparing two numbers will lead you astray; you have to take the time to compute the ratios.
Not surprisingly, Kahan's study found that the more numerate you are, the more likely you are to get the answer to this "skin cream" problem right. Moreover, it found no substantial difference between highly numerate Democrats and highly numerate Republicans in this regard. The better members of both political groups were at math, the better they were at solving the skin cream problem.
But now take the same basic study design and data, and simply label it differently. Rather than reading about a skin cream study, half of Kahan's research subjects were asked to determine the effectiveness of laws "banning private citizens from carrying concealed handguns in public." Accordingly, these respondents were presented not with data about rashes and whether they got better or worse, but rather with data about cities that had or hadn't passed concealed carry bans, and whether crime in these cities had or had not decreased.
Overall, then, study respondents were presented with one of four possible scenarios, depicted below with the correct answer in bold:
The four problem scenarios from the study (each respondent received just one of these)
Dan Kahan
So how did people fare on the handgun version of the problem? They performed quite differently than on the skin cream version, and strong political patterns emerged in the results—especially among people who are good at mathematical reasoning. Most strikingly, highly numerate liberal Democrats did almost perfectly when the right answer was that the concealed weapons ban does indeed work to decrease crime (version C of the experiment)—an outcome that favors their pro-gun-control predilections. But they did much worse when the correct answer was that crime increases in cities that enact the ban (version D of the experiment).
The opposite was true for highly numerate conservative Republicans: They did just great when the right answer was that the ban didn't work (version D), but poorly when the right answer was that it did (version C).
Here are the results overall, comparing subjects' performances on the "skin cream" versions of the problem (above) and the "gun ban" versions of the problem (below), and relating this performance to their political affiliations and numeracy scores:
Full study results comparing subjects' performance on the skin cream problem with their performance on the gun ban problem. Vertical axes plot response accuracy. Horizontal axes show mathematical reasoning ability
@ 59% of people not being able to do basic ratios.
