Book review: How to Predict the Unpredictable, by William Poundstone
"Prediction is very difficult," Danish physicist Niels Bohr said, "especially if it's about the future."
by William Poundstone
Oneworld
3 stars
Steven Poole
"Prediction is very difficult," Danish physicist Niels Bohr said, "especially if it's about the future."
This book doesn't claim to teach you how to predict what is really unpredictable: the weather in a month's time, the next turn of the roulette wheel. A better title is How to Predict the Sort-of Predictable Behaviour of People Who Are Trying to Act Randomly.
When they want to act unpredictably, it turns out, people deviate from true randomness in ways that can be recognised. According to William Poundstone's vivid account, this was first demonstrated by a family of "outguessing machines" created by mathematicians and engineers at Bell Labs in the 1950s.
The outguessing machines played a simple game. Every round, machine and human player pick one of two choices: heads or tails, left or right. If the choices match, one player scores a point, whereas if they are different, the other player scores. What happens is that, over dozens of rounds, humans fall into unconscious patterns a computer can recognise, and therefore anticipate.
In this way, with only 16 bits of memory (16 ones or zeroes), a machine by information theorist Claude Shannon beat all comers. To call this "outsmarting" the humans is perhaps a bit of a stretch, but it is what Poundstone means when he applies it to different areas.
There are a surprising number of areas where a similar "outguessing" strategy can be fruitful. Rock, paper, scissors is a random game, but because most people deviate from true randomness, it is possible to have a strategy. ("A player who loses is more likely to switch to a different throw the next time," he writes.)