September 28, 2010


The following is an excerpt from an article entitled, The Brain's Negative Bias:

Researchers at Duke University Medical Center hooked people up to a high-resolution functional MRI machine (to track the blood flow in the brain) and flashed pictures in front of them. The pictures were of either a square or a circle. They were asked to push a button in their right hand when they saw the square, and push the button in their left hand for the circle.

The squares and circles were presented in a random order, but of course short patterns would sometimes emerge — a string of all squares, for example, or alternation between a square and a circle for several cycles.

Their brains reacted when one of these short patterns ended. Their brains automatically detected and generalized patterns, and very quickly. They were given no reward for detecting patterns. They were not asked to detect patterns. In fact, they were told the pictures would be flashed randomly. Yet still, without any effort on their part, their brains automatically saw patterns in the random events and generalized — began to expect what the next picture would be. In previous similar studies testing their reaction time, the volunteers had a slower reaction time when an expected pattern was broken.

Your brain is predisposed to generalize. It automatically tries to see patterns. And for the most part, our ability to generalize is a good thing. Many moons ago, Ignaz Semmelweis noticed that when a doctor performed a dissection and then assisted in a birth, the women had a tendency to get childbed fever. He was able to detect a pattern, make a generalization, and his ability to generalize led to the practice of using antiseptics and sterilization, saving millions of unnecessary deaths over time.

Charles Darwin was able to create a generalization that governs the evolution of all of life. Quite a generalization! From that single generalization, new understandings about diseases were discovered that greatly improved the effectiveness of doctors. In fact, whole new sciences have issued from that single generalization.

What I'm trying to say is that those mistakes our brains tend to make (like overgeneralizations) are the inevitable secondary results of our great intelligence.

Your ability to recognize a face comes from your brain's ability to complete a pattern with minimal clues. It has been exceedingly challenging to create computers that can do it, and they still aren't as good at it as you are on a bad day without even trying. Your brain recognizes faces without any effort on your part. Your brain is so good at completing a pattern, even in dim light, even if you can only see half of the face, you recognize immediately who it is.

But this amazing ability also sometimes causes us to see patterns that don't really exist. We see a man in the moon. We see a horse in the clouds. We see the big dipper, the little dipper, Orion's belt. Our brains can take the most scant clues and see a pattern, without us making even the smallest effort to do so.

But especially given our brains' bias toward negativity, we also see patterns that create pessimism, cynicism, and defeatism — patterns that our brains have created out of minimal clues — patterns that don't actually exist.

I used to work with a woman who had two failed marriages and concluded, "All men are pigs." From only two examples, she created a generalization that included all three billion men on the planet! Her cynicism, her unwillingness to allow any men to get close to her, was the side-effect of two common mistakes our brains tend to make: 1) the brain's amazing ability to see a pattern with minimal clues, and 2) our brains tendency to look for evidence that confirms an already-existing conclusion.


Once you have concluded something, you have a strong tendency to notice evidence that supports your conclusion and to explain away or ignore information that invalidates your conclusion, not only in your immediate perception, which is bad enough, but also in your memory.

In an experiment, for example, volunteers were asked to read a story about a woman. Let's call her Clare. Two days later, half the volunteers were asked to recall the story and decide how suited Clare was for a career as a real-estate agent. The other half were asked to rate her suitability for a job as a librarian. They were all asked to remember some examples of Clare's introversion and extroversion.

The volunteers looking at her ability as a real-estate agent remembered more examples of Clare's extroversion.

Those assessing her ability as a librarian recalled more instances of Clare's introversion.

The volunteers were not asked to bias their data. They had no stake in the matter. They weren't rewarded in any way to answer one way or another. But that's what human brains do. Your brain naturally and automatically looks at the world and your own memory as if it is trying to confirm whatever conclusions you've already drawn.

You are not the helpless victim of your brain's natural functioning. You can do something about it. But here we're looking at how the virus of negativity can enter the system. We're asking the question: "At what points are we vulnerable to infection?" How do otherwise healthy, reasonable people become pessimistic, cynical, and defeatist? One way is through the natural mistakes human brains are prone to make, combined with the brain's negative bias.

Let's recap. Human brains react more strongly to negative than positive information. They make certain kinds of mistakes in the way they process information — mistakes like overgeneralizing, seeing things in too black-and-white, a tendency to confirm conclusions they have already formed.

And because the brain is already biased toward the negative, those cognitive mistakes are more likely to be made in the direction of pessimism, cynicism, and defeatism.

A form of therapy has sprung up to directly deal with this phenomenon, called cognitive therapy. A cognitive therapist tries to root out the mistakes clients make in their thinking. Those mistakes are causing or sustaining their depression or anxiety. The therapy is simple, straightforward, and short term, and yet it has proven to be surprisingly effective. Cognitive therapy is the most thoroughly-researched form of therapy and when compared to other forms of therapy, it wins. It is the most effective of all therapies, both from objective measurements as well as the clients' own reports.

If you were a client, the most important thing a cognitive therapist would do for you is undermine your confidence in your mistaken conclusions. Overconfidence in our own conclusions is one of the worst mistakes we naturally make. We have a natural propensity — built into the brain — to draw conclusions with insufficient evidence and to hold those conclusions with excessive confidence. And to defend those conclusions with unjustified ardor.

Read more about the dangers of overgeneralizing.

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