February 17, 2015


Your Brain Is Primed To Reach False Conclusions (CHRISTIE ASCHWANDEN, 2/17/15, 538)

Paul Offit likes to tell a story about how his wife, pediatrician Bonnie Offit, was about to give a child a vaccination when the kid was struck by a seizure. Had she given the injection a minute sooner, Paul Offit says, it would surely have appeared as though the vaccine had caused the seizure and probably no study in the world would have convinced the parent otherwise. (The Offits have such studies at the ready -- Paul is the director of the Vaccine Education Center at the Children's Hospital of Philadelphia and author of "Deadly Choices: How the Anti-Vaccine Movement Threatens Us All.") Indeed, famous anti-vaxxer Jenny McCarthy has said her son's autism and seizures are linked to "so many shots" because vaccinations preceded his symptoms.

But, as Offit's story suggests, the fact that a child became sick after a vaccine is not strong evidence that the immunization was to blame. Psychologists have a name for the cognitive bias that makes us prone to assigning a causal relationship to two events simply because they happened one after the other: the "illusion of causality." A study recently published in the British Journal of Psychology investigates how this illusion influences the way we process new information. Its finding: Causal illusions don't just cement erroneous ideas in the mind; they can also prevent new information from correcting them. [...]

Many psychological studies have shown promising improvements in belief accuracy when it involves matters that participants don't care about, Nyhan told me. "But the lesson of controversial political, health and science issues is that people don't apply their critical-thinking skills in the same way when they have a preference for who's right." Studies by law professor Dan Kahan at Yale show that even highly numerate people are prone to cognitive traps when the data contradicts the conclusion most congenial to their political values.

So where does this leave us? With a lot of evidence that erroneous beliefs aren't easily overturned, and when they're tinged with emotion, forget about it. 

Posted by at February 17, 2015 4:11 PM

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