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article imageHow to win 'rock, paper, scissors'

By Tim Sandle     May 4, 2014 in Odd News
Can you win at 'rock-paper-scissors'? What are the odds? You can win consistently, according to a new study, if you follow hidden patterns that you can predict to win more games than you should.
For the uninitiated, 'rock-paper-scissors' is a hand game usually played by two people, where players simultaneously form one of three shapes with an outstretched hand. The "rock" beats scissors, the "scissors" beat paper and the "paper" beats rock; if both players throw the same shape, the game is tied.
The game has been played by children (and adults) for generations. A new study has analyzed the game. The study has revealed that:
In theory, the odds of winning are one-in-three, but only if people play by chance.
However, as people do not often play by chance, then certain strategies can be more successful than others.
Winners tend to stick with their winning action, while losers tend to switch to the next action in the sequence "rock-paper-scissors".
And anticipating these moves could give the player a winning edge.
The strategy was tested out recently in a massive rock-paper-scissors tournament at Zhejiang University in China. According to the BBC, the scientists recruited 360 students and divided them into groups of six. Each competitor played 300 rounds of rock-paper-scissors against other members of their group. As an incentive, the winners were paid in proportion to their number of victories.
To play smart, classical game theory suggests players should completely randomise their choices — to remain unpredictable and not be anticipated by opponents. This pattern — where both players select rock, paper or scissors with equal probability in each round — is known as the Nash equilibrium.
However, NPR blog reports, the organizers noticed a surprising pattern of behavior. When players won a round, they tended to repeat their winning rock, paper or scissors more often than would be expected at random (one in three). Losers, on the other hand, tended to switch to a different action. And they did so in order of the name of the game — moving from rock, to paper, to scissors.
The researchers dubbed this a "win-stay lose-shift" strategy. The researchers argue that it may be hard-wired into the human brain.Studying the game has wider implications, the Cornell University team behind the study argue, for rock-paper-scissors is seen as a useful model for studying competitive behavior in humans, such as with financial trading.
If you want to test out the theory, the New York Times has an on-line game where you can play against a computer: hours of fun ensures.
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