How to win at rock-paper-scissors almost every time

We all know the game. In a detailed study, scientists have observed that player behavior has a surprisingly predictable pattern, and can be exploited when playing the ol’ “two outta three” variation.

After the first move, just know this:

• If a player won, he will usually stick with the same play.
• If a player lost, he will usually switch actions in a clockwise direction: rock changes to paper, paper to scissors, scissors to rock. (Perhaps simpler: HE’LL SWITCH TO WHAT BEAT HIM.)

Example. Say I’m playing rock-paper-scissors with Pierre in order to determine who gets the spot on the couch next to M.

Round 1: Pierre plays paper, I play rock. He wins.
Round 2: Pierre plays paper, I switch to paper. We draw.
Round 3: Pierre plays scissors, I switch to scissors. Another draw. I lose.

But if I’d kept the probabilities in mind, I could have changed my gameplay like so:

Round 1: Pierre plays paper, I play rock. He wins.
Round 2: Pierre plays paper, I switch to scissors. I win.
Round 3: Pierre switches to scissors, I switch to rock. I win again.

Full story at The Washington Post.