A group of mathematicians in China showed that while the strategy of players looks random, it actually consists of predictable patterns that an opponent could exploit to gain a vital edge.
Dr Zhijian Wang recruited 360 students from Zhejiang University who were divided into 60 groups of six players. The players played 300 rounds of rock-paper-scissors against each other and their actions were recorded.
On average, the players in all the groups initially chose each action about a third of the time, which is what would be expected if their choices were random.
However Zhijian’s results showed that players who won the first round of the game tended to stick with the same action while those who lost would switch actions in a “clockwise direction” where rock changes to paper, paper to scissors, scissors to rock.
It was previously thought that players chose each of the three options of rock, paper or scissors equally over time.
Dr Zhijian says that this could be because previous experiments have all been done on a much smaller scale.
He says that it is not clear whether the human response to the game is “built in” to the brain, but that the conclusion that people use a predictable strategy when playing rock-paper-scissors means that the weakness could be exploited:
“Our theoretical calculations reveal that this new strategy may offer higher payoffs to individual players” he said.