Any
Good Books
February
2017
The
Undoing Project: A Friendship That Changed Our Minds
Michael
Lewis (W.W. Norton, 2017)
Amos
Tversky and Daniel Kahneman would have had brilliant careers in
psychology if they had never known each other. Amos worked in
mathematical psychology, and helped write the principal reference on
measurement. He was as lively and outgoing as his chosen subject was
dry, and he could get to the heart of other subjects with shocking
speed, able to appear the smartest physicist in a room full of them.
Danny was the most interesting teacher at Hebrew University, with a
seemingly limitless supply of ideas and questions about why people
act the way they do. At 22, he designed an assessment system for the
Israeli military which helped it make better decisions about
assignments and promotions. He was cut from a different cloth
personally, feeling an acute sensitivity to the opinions of others
where Amos felt none.
But
when they started working together, in 1969, they hit it off like
peanut butter and chocolate. Both had studied at the University of
Michigan before returning to Hebrew University as professors, and one
day Amos came to a seminar Danny was teaching. He came to discuss
some work being done at Michigan about how people judge probability;
the working assumption was that people have an intuitive grasp of
statistical theory, though they sometimes make mistakes in expressing
it. Danny, who had taught statistics, thought that was ridiculous,
and said so; he won the argument that day.
That
fall, Danny and Amos renewed the argument, from the same side. They
devised a test requiring statistical reasoning and tried it out at
meetings of psychologists. "The resulting paper dripped with
Amos's self-assurance, beginning with the title he had put on it:
'Belief in the Law of Small Numbers.'" Their point was that the
Law of Large Numbers doesn't actually apply to small numbers: "Even
people trained in statistics and probability theory failed to intuit
how much more variable a small sample could be than the general
population–and that the smaller the sample, the lower the
likelihood that it would mirror the broader population." Were
psychologists committing such errors in their own work? Certainly
they were; if their experiments gave different results on different
trials, they were far more likely to rationalize the difference away
than to conclude that their samples had been too small.
The
next year, they moved on to the obvious next question:"If people
did not use statistical reasoning, even when faced with a problem
that could be solved with statistical reasoning, what kind of
reasoning did they use?" Danny and Amos identified several rules
of thumb, which they dubbed 'heuristics', that seemed to be operating
when people tried to generalize from partial information. The
heuristic of representativeness applies to things like choosing
athletes in a draft - the front office knows what a pro basketball
player 'looks like', which is a useful rule of thumb, most of the
time–but it would have missed Jeremy Lin and Steph Curry. (It has
since been adjusted to account for them, but who knows what else is
still missing?)
Another
heuristic they called 'availability'. "Any fact or incident that
was especially vivid, or recent, or common–or anything that
happened to preoccupy a person–was likely to be recalled with
special ease, and so be disproportionately weighted in any judgment."
It's why we're always fighting the last war, and doubling our fire
insurance when our neighbor's house has burned. Like other mental
shortcuts, it isn't always wrong–evolution made us this way for a
reason, so to speak–but when it is wrong, we have trouble catching
ourselves. The previously prevalent notion that people are inherently
rational has great big holes in it.
The
hundreds of days, over eight years, that Danny and Amos spent in
closed rooms, arguing in Hebrew and English, shouting and laughing,
gave rise to published work that made everyone think differently.
Their findings were disruptive to academic psychology, not
surprisingly, but also to economics, medicine, history, and sports.
Their lives and academic fortunes diverged in the late seventies, and
they began collaborating with other people, though probably never as
fruitfully as they had together. Michael Lewis has captured a little
bit of their lightning in a bottle, and you may never mistake Man for
a rational animal again.
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