How We Decide

Plato and Descartes taught that important decisions should be made rationally and unemotionally. That’s an elegant idea but not the way our brains really work according to Jonah Lehrer* author of How We Decide (Mariner 2009).

Using MRIs to monitor our brains during the decision process, neuroscientists are discovering:

  1. Our emotional brains are like highly developed supercomputers
  2. By comparison, our rational brains are more like hand-held calculators.
  3. Our rational brains can handle only a few variables at one time – perhaps only four, no more than nine.
  4. For simple decisions defer to reason. If there’s no qualitative difference between products, choose the lowest price. The rational brain likes numbers. Too often we let emotional impulses decide small stuff that’s much better done by invoking reason – like whether to use credit cards.

  5. Complex decisions involving lots of variables can overwhelm the rational brain, e.g. buying a house or a car. Think less about your more important choices and let your emotions choose. Price is a concern of course, but only one variable among the many that contribute to your ultimate satisfaction with what you buy.
  6. Chess is a rational game. That’s why computers can beat grand masters. Poker is both rational and emotional: reason counts the cards but intuition calls a bluff.
  7. If the problem is unique put reason to work. If the problem is really novel emotions can’t save you. Emotions will search your past for a pattern to follow but there is none. The way out of a unique mess is a reasoned creative solution. Emotions aren’t irrelevant however. It helps to be in a good mood when tackling an unprecedented situation. Your prefrontal cortex works better when it’s not busy trying to manage your emotional life.
  8. Embrace uncertainty. Overconfidence in poker or the stock market can lead to disaster. Consider the competing arguments on both sides unfolding in your head. Bad decisions happen when the neural quarrel is cut short. Always entertain competing hypotheses. Continually remind yourself of what you don’t know. Unforeseeable events can undo the most elegant models and theories. Colin Powell demanded of his advisors: “Tell me what you know, and then tell me what you don’t know, and then tell me what you think.”
  9. You know more than you think you do. Your conscious brain is unaware of all the neural activity taking place outside your prefrontal cortex. This is why people have emotions. Emotions are windows into the unconscious -- visceral representations of all the information we process but don’t perceive. That’s why, with its huge computational capacity, the emotional brain is particularly useful in helping us make hard decisions.
  10. Emotions have turned our mistakes into educational events from which we constantly benefit. Wisdom through error. Feelings -- not reason -- capture the wisdom of experience.
  11. But don’t always trust the emotional brain. Instead be constantly aware of the type of decision you’re making and the type of decision process it requires. Study your brain at work. Listen to the argument inside your head.  Think about how you think. Stay aware of how your mind tricks itself into foolish behavior. Become a student of your own errors, determined to learn from what went wrong, and how to avoid them next time.
  12. The most astonishing thing about the human brain is its capacity to improve itself – to improve its decision-making
Lehrer’s book is a bit ragged and I suspect hastily written. A casual reader could lose interest before the above conclusions appear on the last few pages. One more good edit could have remedied these shortcomings. A good editor might have suggested that the book begin with these nuggets. So now forearmed with these nuggets I think you will enjoy How We Decide.
*Jonah Lehrer is an Editor at Large for Seed Magazine and the author of How We Decide and Proust Was a Neuroscientist. He graduated from Columbia University and studied at Oxford University as a Rhodes Scholar. He’s written for The New Yorker, Nature, Wired, The Washington Post and The Boston Globe. He is also a Contributing Editor at Scientific American Mind.

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