It’s widely understood, and pretty common experience, that people who have strong political views tend to see the world as reaffirming their priors. If your Uncle George is a passionate Republocrat, he’ll probably say that everything the Republocrats touch turns to gold while everything under the competing Demolicans becomes a disaster. But you may wonder: Does Uncle George really believe that, or is he just cheerleading for his Republocratic team?

A new study, “Partisan Bias in Factual Beliefs about Politics,” published in the Quarterly Journal of Political Science, suggests that the answer may be a mix. In the study, survey respondents were asked a series of factual questions about major events during the George W. Bush presidency. Sample questions:

Compared to January 2001, when President Bush first took office, has the federal budget deficit in the country increased, stayed the same, or decreased?
About how many U.S. soldiers have been killed in Iraq since the invasion in March 2003? 4,000, 8,000, 12,000, 16,000, or 20,000?

The usual partisan gap occurred, with self-described Republicans asserting a better budget picture and fewer Iraq casualties than self-described Democrats.


Here’s where things get interesting. The authors of the study divided the respondents into two groups. The first group answered the questions with no additional prompts. The second group was given this prompt before answering questions:

For each question that you answer correctly, your name will be entered in a drawing for a $200 gift certificate. For example, if you answer 10 questions correctly you will be entered 10 times. The average chance of winning is about 1 in 100, but if you answer many questions correctly, your chance of winning will be much higher.

The result: The partisan gap in answers in the second group was much smaller than in the first group — about 55 percent smaller. In other words, giving respondents just a small economic incentive to answer correctly produced a different set of answers.

The authors speculate that the answers given absent the incentives are influenced by “political cheerleading,” with respondents saying that their team is great and the other team is bad even though they don’t entirely mean it. The economic incentive trumped at least some of the cheerleading, resulting in a more accurate expression of opinion. According to the authors, “the apparent gulf in factual beliefs between members of different parties may be more illusory than real.”

There’s room to quibble with the study design and the interpretation of the results. But I thought this was a pretty interesting study. For more, see this New York Times story.