A rumor started circulating back in 2008 that Barack Obama was not born in the United States. At the time, I was serving as chair of the Hawaii Board of Health. The director and deputy director of health, both appointed by a Republican governor, inspected Obama’s birth certificate in the state records and certified that it was real.
I would have thought that this evidence would settle the matter, but it didn’t. Many people thought the birth certificate was a fabricated document. Today, many people still believe that President Obama was not born in the U.S.
More recently, I was listening to a “Science Friday” podcast on the anti-vaccination movement. A woman called in who didn’t believe that vaccines were safe, despite overwhelming scientific evidence that they are. The host asked her how much proof she would need in order to believe that vaccines were safe. Her answer: No amount of scientific evidence could change her mind.
As a psychologist, I was bothered, but not shocked, by this exchange. There are several well-known mechanisms in human psychology that enable people to continue to hold tight to beliefs even in the face of contradictory information.
Cognitive shortcuts come with biases
In its early days, the science of psychology assumed that people would make rational decisions. But over the decades, it’s become clear that many decisions people make – about choices ranging from romantic partners and finances to risky health behaviors like unsafe sex and health-promoting behaviors – are not made rationally.
Instead, human minds have a tendency toward several cognitive biases. These are systematic errors in the way you think about the world. Given the complexity of the world around you, your brain cuts a few corners to help you process complex information quickly.
For example, the availability bias refers to the tendency to use information you can quickly recall. This is helpful when you’re ordering ice cream at a place with 50 flavors; you don’t need to think about all of them, just one you recently tried and liked. Unfortunately these shortcuts can mean you end up at a nonrational decision.