Cognitive Dissonance

Editor's Note: The accuracy of the italicized portion of this story has been questioned.

Last week, the BMJ reported that the first paper to claim a link between autism and childhood vaccines - a 1998 study of 12 children by Dr. Andrew Wakefield - was an outright fraud:

The analysis, by British journalist Brian Deer, found that despite the claim in Wakefield's paper that the 12 children studied were normal until they had the MMR shot, five had previously documented developmental problems. Deer also found that all the cases were somehow misrepresented when he compared data from medical records and the children's parents.

Wakefield could not be reached for comment despite repeated calls and requests to the publisher of his recent book, which claims there is a connection between vaccines and autism that has been ignored by the medical establishment. Wakefield now lives in the U.S. where he enjoys a vocal following including celebrity supporters like Jenny McCarthy.

This false causal theory has done a tremendous amount of damage to public health. In Britain, for instance, the Wakefield article led to a sharp decline in vaccination rates for measles: by 2004, only 80 percent of the population was getting the MMR shot. In the United States, more cases of measles were reported in 2008 than in any other year since 1997, according to the CDC.

This blog post is not about why Wakefield is wrong. Instead, it's about what happens when the only piece of evidence in support of a radical idea - vaccines cause autism - is clearly and definitely refuted. I thought this Jenny McCarthy post was sadly illustrative:

I know children regress after vaccination because it happened to my own son. Why aren't there any tests out there on the safety of how vaccines are administered in the real world, six at a time? Why have only 2 of the 36 shots our kids receive been looked at for their relationship to autism? Why hasn't anyone ever studied completely non-vaccinated children to understand their autism rate?

These missing safety studies are causing many parents to approach vaccines with moderation. Why do other first world countries give children so many fewer vaccines than we do? What if a parent used the vaccine schedule of Denmark, Norway, Japan or Finland -- countries that give one-third the shots we do (12 shots vs. 36 in the U.S.)? Vaccines save lives, but might be harming some children -- is moderation such a terrible idea?

This debate won't end because of one dubious reporter's allegations. I have never met stronger women than the moms of children with autism.__ Last week, this hoopla made us a little stronger, and even more determined to fight for the truth about what's happening to our kids__.

That's right: the demonstration of fraud has made McCarthy even more convinced that vaccines cause autism. (It's hard to imagine, then, what kind of evidence might shake her conviction.) I bring this up not to pick on McCarthy, but because I think her paradoxical response reflects a deep seated facet of human nature, an irrational quirk that we are all vulnerable to. This is the theory of cognitive dissonance, first proposed by Leon Festinger, a psychologist at the University of Minnesota. (I've blogged about this before.) In the summer of 1954, Festinger was reading the morning newspaper when he encountered a short article about Marion Keech, a housewife in suburban Minneapolis who was convinced that the apocalypse was coming. (Keech was a pseudonym.) She had started getting messages from aliens a few years before, but now the messages were getting eerily specific. According to Sananda, an extra-terrestrial from the planet Clarion who was in regular contact with Keech, human civilization would be destroyed by a massive flood at midnight on December 20, 1954.

Keech’s sci-fi prophecy soon gained a small band of followers. They trusted her divinations, and marked the date of Armageddon on their calendars. Many of them quit their jobs and sold their homes. The cultists didn’t bother buying Christmas presents or making arrangements for New Years Eve, since nothing would exist by then.

Festinger immediately realized that Keech would make a great research subject. He decided to infiltrate the group by pretending to be a true believer. What Festinger wanted to study was the reaction of the cultists on the morning of December 21, when the world wasn’t destroyed and no spaceship appeared. Would Keech recant? What would happen when her prophesy failed?

On the night of December 20, Keech’s followers gathered in her home and waited for instructions from the aliens. Midnight approached. When the clock read 12:01 and there were still no aliens, the cultists began to worry. A few began to cry. The aliens had let them down. But then Keech received a new telegram from outer space, which she quickly transcribed on her notepad. “This little group sitting all night long had spread so much light,” the aliens told her, “that god saved the world from destruction. Not since the beginning of time upon this Earth has there been such a force of Good and light as now floods this room.” In other words, it was their stubborn faith that had prevented the apocalypse. Although Keech’s predictions had been falsified, the group was now more convinced than ever that the aliens were real. They began proselytizing to others, sending out press releases and recruiting new believers. This is how they reacted to the dissonance of being wrong: by becoming even more certain that they were right.

It's easy to laugh at the alien cultists, or to criticize the empirical ignorance of those pushing the autism/vaccine link. But it's also important to realize that everyone is vulnerable to cognitive dissonance, that we all recoil from information that contradicts a deeply held belief. We live in a world overflowing with information and yet we're still saddled with a brain that knows exactly what kind of information it wants. When the information cuts against our desires, we can't help but double-down. We will believe almost anything to keep our beliefs from being wrong.

PS. If you're interested in the autism/vaccine story, I highly recommend Seth Mnookin's new book.