Most of us prefer to think of ourselves as logical beings. While we may not be dispassionate thinkers like Mr. Spock, we’re confident that facts play a predominant role in our decisions. But our brains aren’t wired like our green-blooded friend. When faced with the human brain, logic and evidence-based thinking encounter a formidable opponent.

spockIn large part, you can blame this on biology. Critical thinking is physically taxing and frequently outranked by the more pressing needs of the body. And then there’s the not-so-insignificant problem of confirmation bias.

Confirmation bias is the brain’s tendency to only seek out information, or interpret that information, in ways that reinforce our pre-existing views. Not only does this clever trick protect us from having to admit we’re wrong, it also allows us to maintain our notions of being logical thinkers while we simultaneously disregard facts. Well played, brain.

The impact of confirmation bias

Confirmation bias affects your thinking on everything from political candidates to how you make decisions in the workplace. You might spot confirmation bias in the social media manager who is overstating the impact of Facebook on overall revenue. You might see confirmation bias at work with your uncle who believes that all women are bad drivers, and “proves it” with a single encounter at the grocery store parking lot.

If you’re reading this article and thinking, “I’ve totally seen other people do this!” while you regale yourself with examples of your own logical thinking…well…there’s probably some confirmation bias at work. We have all fallen victim to this problem at one point or another. Not convinced? Let’s look at two broader examples.

The hot hand

In 1985, the glory of the 76ers carried the spirit of Philadelphia (remember Dr. J?). Players seemingly made shot after shot after shot. If someone was on a streak, the player, the coaches, and the fans shared the belief that they couldn’t be stopped — not while they had a hot hand. This made the team a good subject for a psychological study of confirmation bias. The study examined whether there was any truth in the phenomenon: were players more or less likely to score after a basket?


Look at the column labeled P(hit/3 hits). This should be the one that proves the existance the hot hand. It’s measuring the probability of a player making a fourth hit after three in a row. And it firmly disproves the idea. In fact, players were statistically more likely to score after one or more misses.

How did so many people miss seeing this? When it comes to winning streaks, we simply disregard all the far more normal times that a third basket leads to a miss. Four in a row is more memorable, which supports our bias towards believing in the existence of a hot hand.

Charles Mackay, author of Extraordinary Popular Delusions and The Madness of Crowds, summed up these beliefs perfectly writing, “When men wish to construct or support a theory, how they torture facts into their service!”

Improbability of premonitions

Let’s move into eerier psychological territory. You probably know someone who has had this macabre experience. They probably whispered when they told you. “I had a dream that my Uncle Frank died, and when I woke up I had a voicemail from my mom. When I called her back she told me Frank had a sudden heart attack and died in his sleep. Isn’t that weird?” You’re left thinking the dream accurately predicted the death, and possibly a little wary of what your friends dream about you.

Michael Shermer of Scientific American put numbers to this issue:

The average person has about five dreams a night, or 1,825 dreams a year. If we remember only a tenth of our dreams, then we recall 182.5 dreams a year. There are 300 million Americans, who thus produce 54.7 billion remembered dreams a year. Sociologists tell us that each of us knows about 150 people fairly well, thus producing a social-network grid of 45 billion personal relationship connections. With an annual death rate of 2.4 million Americans, it is inevitable that some of those 54.7 billion remembered dreams will be about some of these 2.4 million deaths among the 300 million Americans and their 45 billion relationship connections. In fact, it would be a miracle if some death premonition dreams did not happen to come true!

This example of seemingly supernatural storytelling is really just our brains trying to make sense out of chaos. By trying to create reason, we ultimately erase it.

Why does this happen?

Even scientists are not immune to this odd bit of reasoning. Nobel Prize winning physicist Max Planck wrote, “A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.” This is a strong statement to make about a group of people known for their love of evidence and research.

And if scientists are susceptible, assume that you are too. Our core beliefs are a part of our self-identification. When presented with facts that contradict an incorrect idea, we become more likely to just grasp it harder. Releasing even a single factually incorrect belief can chip at our idea of self. Most of us find that experience unpleasant, and our brains will work overtime to avoid it. But there is a way.

Fighting confirmation bias

Rejecting incorrect beliefs takes work. Warren Buffett wrote about one of his rejection heroes:

Charles Darwin used to say that whenever he ran into something that contradicted a conclusion he cherished, he was obliged to write the new finding down within 30 minutes. Otherwise his mind would work to reject the discordant information, much as the body rejects transplants. Man’s natural inclination is to cling to his beliefs, particularly if they are reinforced by recent experience–a flaw in our makeup that bears on what happens during secular bull markets and extended periods of stagnation.

Tempting as it is to jump into battle against the confirmation bias of other people, you’re far better off looking inward. Force yourself to see the merit in opposing arguments. Expose yourself to new data sets and information. Be aware that confirmation bias exists, and admit that you (yes, even you) will occasionally fall victim to it.