Carl%20Sagan%20-%20The%20Demon%20Haunted%20World

THE DEMON-HAUNTED WORLD
three-point baskets from all over the floor that he shrugged his
shoulders in amazement at himself. In contrast, there are times
when you're cold, when nothing goes in. When a player is in the
groove he seems to be tapping into some mysterious power, and
when ice-cold he's under some kind of jinx or spell. But this is
magical, not scientific thinking.
Streakiness, far from being remarkable, is expected, even for
random events. What would be amazing would be no streaks. If I
flip a penny ten times in a row, I might get this sequence of heads
and tails: HHHTHTHHHH. Eight heads out of ten, and four
in a row! Was I exercising some psychokinetic control over my
penny? Was I in a heads groove? It looks much too regular to be
due to chance.
But then I remember that I was flipping before and after I got
this run of heads, that it's embedded in a much longer and less
interesting sequence: HHTHTTHHHTHTHHHHTHT
T H T H T T. If I'm permitted to pay attention to some results and
ignore others, I'll always be able to 'prove' there's something
exceptional about my streak. This is one of the fallacies in the
baloney detection kit, the enumeration of favourable circumstances.
We remember the hits and forget the misses. If your
ordinary field goal shooting percentage is 50 per cent and you
can't improve your statistics by an effort of will, you're exactly as
likely to have a hot hand in basketball as I am in coin-flipping. As
often as I get eight out of ten heads, you'll get eight out of ten
baskets. Basketball can teach something about probability and
statistics, as well as critical thinking.
An investigation by my colleague Tom Gilovich, professor of
psychology at Cornell, shows persuasively that our ordinary
understanding of the basketball streak is a misperception.
Gilovich studied whether shots made by NBA players tend to
cluster more than you'd expect by chance. After making one or
two or three baskets, players were no more likely to succeed than
after a missed basket. This was true for the great and the
near-great, not only for field goals but for free throws - where
there's no hand in your face. (Of course some attenuation of
shooting streaks can be attributed to increased attention by the
defence to the player with the 'hot hand'.) In baseball, there's the
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