Rock-paper-scissors is a old children's game, known to people worldwide largely as a game of chance, but there may be a way to win.
In the competition, people make shapes of either a rock, piece of paper or a pair of scissors. Simple rules dictate who wins each round. The game would seem to be entirely random, but a group of mathematicians from China believe they have found a way to win the game nearly every time.
Zhijian Wang of Zhejiang University in China studied 360 students, divided into 50 groups of six players each. To encourage them to win, Wang paid each of the subjects a small amount of money for each victory.
Each of the subjects played 300 rounds of the game, while researchers recorded the strategies - and results - of all the participants. As subjects played round after round of rock-paper-scissors, investigators searched, looking for patterns in the way people play. They found an intriguing pattern to this simple game.
When people win a round of the contest, they usually stick to the same choice of rock, paper or scissors, perhaps subconsciously believing that what worked once will work again. After a losing round, participants usually change tactics, making a different choice for the following turn.
Also, players on losing streaks tend to make increasingly powerful choices. For instance, after losing with scissors, most people will play rock. Failing that round, they will gravitate toward paper.
Mathematicians studying this behavior refer to it as a "conditional response."
Taking advantage of this in real-life games is dependent on wins and losses. After a player wins with scissors against paper, their opponent will likely choose rock next, making paper the winning move. After losing with paper against scissors, the best odds come from selecting what would beat the opponents last choice, which is rock.
Rock-paper-scissors can be dated back almost 2,000 years to China, where the game was first called "Hand command." In the original format, an outstretched hand represented a cloth sheet. The practice then migrated to Japan, where it was adapted by the people there, who changed the sheet to paper, and modified the scissor shape. By the early 20th century, rock-paper-scissors was being played in the United States and Europe. By the end of the 1920's, the games we at the crest of fashion. Movies were playing in theaters titled Scissors Cut Paper (1927) and Stone Blunts Scissors (1929). Three years later, the New York Times wrote an article explaining the rules of the game to the masses.
A robot player at the University of Tokyo has a perfect record at the game. Using video cameras, the mechanized player can recognize a human player's move within a millisecond of seeing the hand.
Study of rock-paper-scissors is detailed in the Arvix catalog.