You Are Not So Smart: Why You Have Too Many Friends on Facebook, Why Your Memory Is Mostly Fiction, and 46 Other Ways You're Deluding Yourself

by David McRaney

Cognitive biases are predicable patterns of thought and behavior that lead you to draw incorrect conclusions.

You can prime potential employers with what you wear to a job interview. You can prime the emotions of your guests with how you set the mood when hosting a party. Once you know priming is a fact of life, you start to understand the power and resilience of rituals and rites of passage, norms and ideologies. Systems designed to prime persist because they work. Starting tomorrow, maybe with just a smile and a thank-you, you can affect the way others feel—hopefully for the best.

If someone you know gets sick from taking a flu shot, you will be less likely to get one even if it is statistically safe. In fact, if you see a story on the news about someone dying from the flu shot, that one isolated case could be enough to keep you away from the vaccine forever. On the other hand, if you hear a news story about how eating sausage leads to anal cancer, you will be skeptical, because it has never happened to anyone you know, and sausage, after all, is delicious. The tendency to react more rapidly and to a greater degree when considering information you are familiar with is called the availability heuristic.

In a mystery like The Da Vinci Code, or in a television series like Lost, where mysterious happenings are at the center of the plot, clues pop up that turn out to be connected in some strange way. You can’t help but be intrigued by the patterns slowly coalescing. It drives you crazy. You find yourself compelled to keep turning the page or popping in the next disc to see what happens, to see how everything connects in the end. When you do this in the real world, it is called apophenia.

J. E. Littlewood, a mathematician at Cambridge University, wrote about the law of truly large numbers in his 1986 book, Littlewood’s Miscellany. He said the average person is alert for about eight hours every day, and something happens to the average person about once a second. At this rate, you will experience 1 million events every thirty-five days. This means when you say the chances of something happening are one in a million, it also means about once a month. The monthly miracle is called Littlewood’s Law.

A group of people sits around a table, and each person is given a few dollars. The group is told they can put as much money as they want in the community pot. An experimenter then doubles the pot, and everyone then gets an equal portion back. If it’s ten people and everyone gets $2, and everyone puts in that money, the pot would be $20. It gets doubled to $40 and divided by ten. Everyone gets back $4. The game proceeds in rounds, and you would think everyone would just put the maximum amount in the pot each time—but they don’t. Someone usually gets the gist of the game and realizes that one can put in very little, or nothing at all, and start making more money than everyone else. If everyone but you puts in $2, the pot would be $18. It gets doubled to $36 and everyone gets back $3.60—including you, the one who put nothing in at all. In experiments where this game is played so everyone can see who puts in a fair share, the pot tends to grow for a while and then it starts to shrink as people test the water by withholding funds. The behavior spreads, because no one wants to be a chump, and eventually the economy grinds to a halt. If people are allowed the option of punishing cheaters, the cheating stops, and everyone wins. If instead of punishment, people are given the choice to reward good players, the economy again crashes after a few rounds. The crazy thing about this game is how illogical it is to stop contributing just because someone in the group is free riding. If ever...

In one experiment, he got fifty-four oenology (the study of wine tasting and wine making) undergraduates together and had them taste one glass of red wine and one glass of white wine. He had them describe each wine in as much detail as their expertise would allow. What he didn’t tell them was both were the same wine. He just dyed the white one red. In the other experiment, he asked the experts to rate two different bottles of red wine. One was very expensive, the other was cheap. Again, he tricked them. This time he had put the cheap wine in both bottles. So what were the results? The tasters in the first experiment, the one with the dyed wine, described the sorts of berries and grapes and tannins they could detect in the red wine just as if it really was red. Every single one, all fifty-four, could not tell it was white. In the second experiment, the one with the switched labels, the subjects went on and on about the cheap wine in the expensive bottle. They called it “complex” and “rounded.” They called the same wine in the cheap bottle “weak” and “flat.”