Big Thing has an essay about the backfire effect, the name given to a well-established psychological phenomenon whereby people actually become more entrenched in a false belief when confronted with evidence that shows that belief to be incorrect.
This horrifying phenomenon known as the backfire effect was demonstrated once again recently by a study of the responses of parents to various different forms of evidence that vaccines are not dangerous. The randomized controlled trial drew from four CDC sources, all designed to use scientific evidence to demonstrate why children must be vaccinated…
In all four cases, none of the materials increased parents intentions to vaccinate their children. The effects of the straight forward information about measles, mumps and rubella were fairly neutral. The images of children with measles, mumps and rubella and the mother’s narrative about her hospitalized child both had the unintended effect of increasing beliefs in vaccine side effects. The images also somehow increased false beliefs that vaccines cause autism. The material that refuted the MMR-autism link successfully reduced false beliefs about the idea that vaccines cause autism but astoundingly actually reduced the intent to vaccinate in parents with the most anti-vaccine beliefs.
This isn’t the first time we’ve seen depressing findings from studies attempting to refute vaccine myths. A study described in a paper by Schwarz et al, found that a CDC flyer containing “facts and myths” about vaccines increased intentions to vaccinate immediately but had the opposite effect after only half an hour – when the participants began remembering the myths as facts. It seems we really are glorified goldfish when it comes to remembering the separation between fact and fiction. When the experimenters created a version of the flyer where myths were rephrased as facts the flyer successfully increased intention to vaccinate, this contrasted with the original CDC flyer which left participants off worse than when they started. Avoiding reference to myths is far from a perfect solution however, because it fails to directly address the myths that are in circulation.As if things couldn’t get any more depressing, Norbert Schwarz the coauthor of the “facts and myths” paper suggests that when a respected institution such as the CDC weighs in and debunks a claim, this can actually end up lending credence to the claim in people’s minds. Schwarz cites as an example an internet rumor about flesh-eating bananas that was so prolific it was debunked by the CDC website. When this happened, the flesh-eating banana scare grew and began actually being attributed to the CDC!
What does this say about human cognition and our ability to use reason? Nothing good, I imagine, though I’m hardly learned enough in the psychological literature to address this particular phenomenon. I wonder if Dr. X and others with some training in psychology and cognitive neuroscience might weigh in on it?