Learn how to become a rock-paper-scissors champion using science

Most of us approach maths with a healthy respect and a little bit of fear. After all, maths has done everything from build the pyramids to land a space probe on a comet.

And now the subject dreaded by school pupils everywhere has added another string to its bow – it’s “solved” the game of rock-paper-scissors.

Who’s done this?

A group of scientists in China have undertaken some pretty time-consuming experiments to find the best tactics for the classic children’s game. They’ve written up their findings here. And, classic scientists, they’ve even turned the game into an acronym (RPS).

They took 360 students (all doing different subjects) at Zhejiang University, sorted them into groups, and made them play rock-paper-scissors 300 times against various opponents. This tended to take anywhere between 90 minutes and two and a half hours.

What did they discover?

Since the probability of your opponent picking either of the three options is the same, in theory no patterns should have emerged – at least they wouldn’t have if a truly random computer programme was doing it. But –  unlike computers – humans can’t help rationalising things.

Two basic principles were observed during the trials.

1. Winners from the previous game tended to stick with their previous choice. (And why not, if it won once it’ll do it again – right?)

2. Losers from the previous game tended to pick the option that would have beaten their opponent in the previous game.

The researchers recognised that game theory could be applied here. For anyone who wants to know more about this, watch A Beautiful Mind starring Russell Crowe as a gravel-throated version of mathematician John Nash.

So how can I use this to win?

Now we get to the juicy part of the findings – the part that could change your life LITERALLY forever.

There are a couple of basic rules that can help you win a game of rock-paper-scissors.

1. If you win the first round, play the thing your opponent just played. They’ll most likely be expecting you to stick and therefore switch to the choice that beats your first hand.

2. If you lose the first round, switch to whatever wasn’t played before. Having won, your opponent is most likely to stick.

These tactics aren’t foolproof, but probability says that over a number of games you should triumph.

Of course this won’t help you win the first round because you’ve got no information to go on yet. Also there’s always the risk your opponent has read about this self-same study…


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