Photo credit: Gérard DuBois
By Derek J. Koehler
Given the complexities of the modern world, we all have to rely on expert opinion. Are G.M.O. foods safe? Is global warming real? Should children be vaccinated for measles? We don’t have the time or the training to adjudicate these questions ourselves. We defer to the professionals.
And to find out what the experts think, we typically rely on the news media. This creates a challenge for journalists: There are many issues on which a large majority of experts agree but a small number hold a dissenting view. Is it possible to give voice to experts on both sides — standard journalistic practice — without distorting the public’s perception of the level of disagreement?
This can be hard to do. Indeed, critics argue that journalists too often generate “false balance,” creating an impression of disagreement when there is, in fact, a high level of consensus. One solution, adopted by news organizations such as the BBC, is “weight of evidence” reporting, in which the presentation of conflicting views is supplemented by an indication of where the bulk of expert opinion lies.
But whether this is effective is a psychological question on which there has been little research. So recently, I conducted two experiments to find out; they are described in a forthcoming article in the Journal of Experimental Psychology: Applied. Both studies suggest that “weight of evidence” reporting is an imperfect remedy. It turns out that hearing from experts on both sides of an issue distorts our perception of consensus — even when we have all the information we need to correct that misperception.
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