In one perseverance study, participants tried to distinguish between real and fake suicide notes. In fact, regardless of what they said, half the people were told they were right most of the time (the “success” condition), while the others were usually told they were wrong (the “failure” condition). Later, the participants were debriefed. It was explained that the feedback was false and that they had been randomly assigned to success and failure conditions. Even though they understood the debriefing, the “successful” people still believed they were better at the task than those who had “failed” thought they were.
Perseverance affects people's reactions to scientific studies that support or contradict their beliefs. Another experiment involved students with contrasting attitudes, some who believed that capital punishment was a deterrent to murder and others who rejected this claim. People in both groups read summaries of two fictitious studies, one which supported the deterrence hypothesis and one which didn't. You might think reading mixed evidence would lead people to moderate their beliefs. However, both pro- and anti-deterrence participants became more convinced of their original beliefs—a backfire effect. The two groups' beliefs became more polarized.
Perseverance studies seem to suggest that fact-checking politically biased claims is a losing effort. Recent research suggests that more educated and well-informed people show greater perseverance, since having more information allows them to explain away contradictory findings more easily. The Nyhan study is in that tradition. Here is Dr. Ubel explaining the study.
The chart below shows the results. On the left are the low knowledge participants. Without the correction, those who liked Palin believed the death panel myth, but the rebuttal was effective in disabusing them of this belief. However, the high knowledge Palin supporters believed the death panel myth more with the correction than without it. The correction backfired.
Just a word of caution. I was fully prepared to believe this study; however, the more I thought about it, the more I sympathized with the high information Palin supporters. The rebuttal to Palin's claim read (in its entirely) as follows:
However, non-partisan health care experts have concluded that Palin is wrong. The bill in the House of Representatives would require Medicare to pay for voluntary end-of-life counseling sessions, but there is no panel in any of the health care bills in Congress that judges a person's “level of productivity in society” to determine whether they are “worthy” of health care.
Should a well-informed Republican really be satisfied with this rebuttal? If I were in their shoes, I might want to ask some additional questions. Who are these “non-partisan experts?” The correction addresses Palin's claim about end-of-life counseling, but what about the Patient-Centered Outcomes Research Institute, which is charged with evaluating the effectiveness of medical treatments, and the Medicare Independent Payment Advisory Board, which is supposed to refuse to pay for expensive but ineffective treatments? How much indirect control will they have over the treatment patients actually receive? I personally hope these groups will help to eliminate wasteful procedures, but since they haven't met yet, we don't really know.
I'm not questioning the existence of perseverance, or that it makes researchers' lives a lot more difficult. However, another way to read this study is that well-informed people may require more detailed counterarguments than these authors provided.
