How To Win Rock, Paper, Scissors

Since my daughter started school, my life has become an endless series of games of Rock, Paper, Scissors. She has decided that this is the only fair way to settle any argument, make any decision or fill any empty moment of time.

For those who have been living under a rock (or paper or scissors) the game is simple. On the count of three, players make the hand gesture for either rock, paper or scissors.

Rock beats scissors. Scissors beats paper. Paper beats rock.

In 2006, a US federal judge ordered competing lawyers to settle a trivial disagreement via a legally binding game of rock paper scissors. In 2015, Police in the UK let a woman off with a warning for underage drinking after she beat them at a round of the game. In a 2018 match in the FA Women's Super League, the referee, unable to find a coin for the coin toss, had the captains play rock paper scissors to determine which team would kick-off.

So how do you get an edge?

It appears, at first glance, to be impossible. Rock paper scissors is a zero-sum game. Every player has exactly the same chance of winning. No particular hand gesture has an edge over the other two. The game is 100% fair, transparent and accessible.

So, instead of playing the game, you have to play the player.

It has been suggested that a keen eyed player can watch the their competitor's fist and anticipate what they are about to play. In theory, if you watch the other players hand as it rises and falls, you may begin to see subtle tells that reveal their intentions.

If that sounds far fetched, a robot was trained to do exactly this at Ishikawa Senoo Laboratory in 2012.

You can also analyse previous games to gain an edge. According to Lily Serna in her book Curious, rock paper scissors players can increase their chances of winning by considering the patterns of behaviour people tend to make when playing multiple games. According to Serna's research:

1) Winners are likely to repeat winning moves.

2) Losers are likely to play the move that would have beaten the winner.

If you lose your first game, the best course of action is to play the gesture that would have beaten that player. e.g If you play PAPER against SCISSORS and lose, you should play ROCK in the next round.

If you win your first game, the best course of action is to copy the losing player in the next game. e.g. If you play SCISSORS against PAPER and win, you should play PAPER in the next round.

While this technique won't guarantee that you win every round, it will increase your chances over time. The more rounds you play, the more likely you are to come out ahead.

Even if your competitor is a six-year-old who wants to watch Paw Patrol for six hundredth time.