Correlation is not causation

Flu vaccinations make their way to U.S. Army in Europe 

Your Brain Is Primed To Reach False Conclusions
[Via FiveThirtyEightFiveThirtyEight | Features]

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.

Helena Matute, a psychologist at Deusto University in Bilbao, Spain, and her colleagues enlisted 147 college students to take part in a computer-based task in which they each played a doctor who specializes in a fictitious rare disease and assessed whether new medications could cure it.


We look for patterns, even when they do not exist. As the article demonstrates, it is so easy to be fooled into thinking a particular treatment cures the illness.

And when dealing with something as complex as human health, it becomes easy to see how people can go down the wrong path. Other data shows that once many people go down that wrong path, it is very hard to turn off of it.

Since only about 15% of people  examine things analytically, facts may not matter. The rest simply use rapid, gut-level thinking to make decisions. 

Simple narratives for complex subjects. It appears that the best approach is not to get them tosee the facts. They will not deop into analytical thinking.

One has to create better metaphors.