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How AI thinks: Rock, Paper, Scissors and the magic of probability

  • Writer: Frobo
    Frobo
  • Jun 27
  • 2 min read
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Have you ever played Rock, Paper, Scissors with your friends? It’s a fun and fast game where you try to beat the other person by picking the right move. Guess what? AI can learn how to play this game too — and even get really good at it.


How? That’s where something called probability comes in!


🧠 What is AI?

AI doesn’t think exactly like humans, but it can learn from patterns. So if you play Rock, Paper, Scissors with it 100 times, it can remember what you usually pick and try to outsmart you!


🎲 What is probability?

Probability is a fancy word for how likely something is to happen. Imagine you have a bag with 1 red marble and 9 blue marbles. If you close your eyes and pick one, you’ll probably get blue, right? That’s because there are more blue ones.


So, probability is all about guessing what might happen, based on what we know.

In Rock, Paper, Scissors:

  • You have 3 choices.

  • If everyone played totally randomly, each move (Rock, Paper, or Scissors) would have a 1 out of 3 chance — that’s about 33% for each one.


But humans don’t always play randomly. We repeat moves, or switch in patterns without realising it.


🧠 How AI uses probability to win

Let’s say you’re playing with an AI robot.


At first, the AI doesn’t know anything. It just guesses like a normal player:

  • Rock? 🤜

  • Paper? ✋

  • Scissors? ✌️Each has a 1-in-3 chance.


But then the AI starts watching what you pick.


Maybe after 10 games, it notices:

  • You pick Rock 50% of the time,

  • Paper 30%,

  • Scissors 20%.


Now the AI uses probability to predict what you might do next. It thinks,“Hmmm… this kid really likes Rock, so I’ll use Paper more often, since Paper beats Rock!”


Now the robot isn’t just guessing — it’s using smart guessing based on your history.


🧪 A quick example

Let’s say you’ve played 5 rounds like this:

  1. Rock

  2. Rock

  3. Paper

  4. Rock

  5. Paper

The AI might think:

  • You picked Rock 3 times (60%)

  • Paper 2 times (40%)

  • Scissors 0 times (0%)

So, what should the AI do next?If it thinks you’ll pick Rock again, it should play Paper to win!


🤖 So is AI magic?

Nope! It’s just really good at keeping track of patterns and using probability to guess the best move. The more it plays, the smarter it gets. Just like how you get better at games the more you practice.


🏁 Final Thought

AI isn’t just used in games — it helps drive cars, recognise voices (like when you ask Alexa a question), and even recommend your next favorite YouTube video. But at the heart of many of these things is the same idea: watch what happens, guess what might happen next — that’s probability!

So next time you play Rock, Paper, Scissors… just know: you’re also learning how to think like an AI! 🤯


Keep playing.


Ribbit, ribbit,

//Frobo

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