Rock • Paper • Scissors Picker

What this picker does

So you want to throw rock, paper, or scissors, but there is no one to play against, or you just want the game to pick for you. Tap Generate and it gives you one of the three, at random. That is it. Use it to make your throw for you, to settle a quick decision the rock paper scissors way, or to be the neutral hand when two people cannot agree.

How to use it

1. Tap Generate.
2. It thinks for half a second, then shows Rock, Paper, or Scissors.
3. Tap again for a fresh one.

Each tap is a new pick, so go as many rounds as you need.

How it works

The picker uses your browser's random generator, Math.random, to choose one of the three options with an equal one in three chance each. There is no pattern and no memory, so the last result has no effect on the next. It runs entirely on your device.

The usual honest note, Math.random is pseudo random rather than true physical randomness, which is completely fine for a game like this.

Why random actually wins this game

Here is the interesting bit. The best possible strategy in rock paper scissors is to be completely random, because then your opponent has nothing to read. The catch is that humans are terrible at being random. A well known 2014 study from Zhejiang University watched 360 people play 300 rounds each and found a clear habit, players who win tend to repeat the move that just won, and players who lose tend to switch to a different one. It is called win stay, lose shift, and it makes people predictable.

There is another known tendency, beginners throw rock more often than they should, probably because it feels strong. So two small tips if you are up against a real person. Open with paper, since rock is the common first throw. And if your opponent just won with scissors, do not be surprised if they reach for scissors again. A genuinely random pick, like the one this tool makes, has none of those tells, which is exactly why it is so hard to beat.

What people use it for

Use it to settle who gets the last slice, who goes first, or who is stuck with the chore nobody wants. It is also good for practice, since playing against a truly random hand stops you leaning on your own habits. And when two friends each insist the other should choose, it makes a fair call that nobody can argue with.

Questions people ask

References

1. Wang, Z., Xu, B., and Zhou, H. J. Social cycling and conditional responses in the Rock-Paper-Scissors game (2014). https://arxiv.org/abs/1404.5199
2. MDN Web Docs. Math.random(). https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/random