# The One Little Trick to Help You Win at Rock-Paper-Scissors More Often

It’s one of the simplest ways to settle a dispute fairly: rock-paper-scissors. But it turns out those who learn to make a simple observation might gain an advantage at turning the odds in their favor.

Rock-paper-scissors, also known as roshambo, is a game where each user makes one of the respective shapes with their hand, rock smashing scissors, scissors cutting paper and paper covering rock.

Mathematicians at Zhejiang University in China conducted an experiment and observed that while a player’s choice of hand motions might look random, they actually follow predictable patterns that can be exploited for a competitive edge.

The researchers recorded 360 students who were randomly paired to play rock-paper-scissors and who had the incentive of a financial payout for the number of times they won. While they observed each player choosing rock, paper or scissors equally, adhering to what game theory probabilities in these cases, they also saw that a players choice in two consecutive moves was not independent but correlated.

“At each time the players are more likely to repeat their last action than to shift action either counter-clockwise (i.e., R → P, P → S, S → R) or clockwise (R → S, S → P, P → R),” the study authors wrote.

“This game exhibits collective cyclic motions which cannot be understood by the Nash equilibrium concept but are successfully explained by the empirical data-inspired [conditional response] mechanism,” the authors continued in their discussion.

The researchers pointed out that a “win-stay lose-shift strategy” — one where a player will be more likely to keep a gesture if they just won and change it if they just lost — “appears to be psychologically plausible for human subjects with bounded rationality.”

If this is the case, it could help you better predict your opponent’s next move in order to overtake them. For example, if your opponent had just won with rock, there’s a higher chance that they might play rock again, meaning it might be a good time for you to play paper.

Conversely, if you were the winner with scissors, consider switching to paper because the odds are higher in this case that your opponent might play rock in the hopes of beating a repeated scissor move.

This logic will not work, however, if you’re battling this rock-paper-scissors wizard robot, which cheats by watching the movement your hand is making a millisecond before you throw down.

(H/T: Daily Mail)

Front page image via Shutterstock.