We now have computers that can predict the weather and help cure cancer. So what do people use them for? Determining the best way to play Rock, Paper, Scissors.

In case you somehow missed your childhood, The Word Detective described the game in 2012, quoting from the Oxford English Dictionary: “’A game (used especially to settle petty disputes or as a tiebreaker) in which, at an agreed signal, each participant makes a gesture with one hand representing either a rock, paper, or a pair of scissors, the winner being determined according to an established scheme,’ which is usually ‘rock blunts (beats) scissors, scissors cut paper, paper wraps rock.’ There is almost always a three-syllable counting phrase (or just ‘one, two, three’) chanted during the game, which consists of two warm-up feints and then a third swing of the arm when your choice of R, P or S is displayed.”

(Regionally, the game is sometimes known as Roshambo, the derivation of which Word Detective was unable to ascertain.)

Rock, Paper, Scissors dates back as far as the second century B.C. in China, according to Word Detective. In the mid-19th century, a law was passed in England declaring an RPS match “between two gentleman acting in good faith” to be a legally binding contract, the site writes. It’s even thought to be used in the animal kingdom.

Consequently, there is also a World RPS Society, founded in London in 1842 as the Paper Scissors Stone Club, with a website including tips on strategy, variants, and the history of the game. For example, there are actual names for a number of combinations of three moves (such as “Avalanche” for a series of three “Rock” moves). The site also includes a number of strategies to be used when playing against humans. “Humans, try as they might, are terrible at trying to be random,” writes Graham Walker, co-author of the Official Rock Paper Scissors Strategy Guide and five-time organizer of the World Rock Paper Scissors Championships. “In fact often humans in trying to approximate randomness become quite predictable.”

Anyway, like a similar game, Prisoners Dilemma, over the years people have turned the awesome power of computers toward determining the very best strategy on how to win. In fact, like Prisoners Dilemma, tic tac toe, and chess, computer experts turn back to the problem every few years to leverage improvements in hardware and software over that time. (Some versions even cheat.)

More generally, developing versions of Rock, Paper, Scissors is good practice for studying other computer science fields, according to the site RPSContest.com. “Although rock-paper-scissors (RPS) may seem like a trivial game, it actually involves the hard computational problem of temporal pattern recognition,” the site notes. “This problem is fundamental to the fields of machine learning, artificial intelligence, and data compression. In fact, it might even be essential to understanding how human intelligence works.”

For example, in 2011 the New York Times developed an artificial intelligence version of the game that could either “learn” strategy by playing against you, or by using its library of 200,000 possible moves to determine its strategy. The interesting aspect of this version is that you can choose to examine the strategy the program is using.

Similarly, the techniques learned by playing Rock, Paper, Scissors can also be applied to all sorts of other realms of trying to predict human behavior, whether it’s Target figuring out when women are pregnant or Siri determining what people are asking for, writes William Poundstone in his book Rock Breaks Scissors: A Practical Guide to Outguessing and Outwitting Almost Everybody.

Numerous academic papers have also been written on the subject, such as a recent one by three Chinese universities that studied a population of 360 Rock, Paper, Scissors players. “Let’s say you’re playing best three out of five and you lose the first game,” writes John Wenz in Popular Mechanics. “According to the science, you should then play whatever would have beaten your opponent’s previous hand. In other words, if you dropped scissors and your opponents beat you with rock, then play paper in round two. That’s because people who find success tend to try what worked.”

Think this is all a lot of effort for what’s just a silly children’s game? In 2005, a Japanese art collector used Rock, Paper, Scissors to decide whether to use Christie’s or Sotheby’s to sell his $20 million art collection—a deal that would make the winning company $1.9 million in fees. The Christie’s representative ended up winning –by depending on the advice of the 11-year-old twin daughters of her boss.

“Everybody knows you go scissors,” one of the daughters said.

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