In China, a team of researchers tapped 360 students to try to crack the ever-important nut: how do people play Rock, Paper, Scissors? And what's the best strategy?
People start by picking each variable (rock, paper or scissors) about one-third of the time. You can’t really game this stage. BUT after the first round:
If a player wins, he will usually stick with the same play.
If a player loses, he will usually switch actions in “a clockwise direction”: rock changes to paper, paper to scissors, scissors to rock.
So that's it. If you know what someone will play next, it's easy to counter and achieve a grand victory.
But wait, what if they know the strategy, too? And they try to predict and out-smart your next move? But then you, knowing that they know, try to preempt their prediction? Then they, knowing you know they know...
When playing with someone who is not experienced at the RPS, look out for double runs or in other words, the same throw twice. When this happens you can safely eliminate that throw and guarantee yourself at worst a stalemate in the next game. So, when you see a two-Scissor run, you know their next move will be Rock or Paper, so Paper is your best move.
The researchers in China weren't just trying to work out the strategy to a schoolyard game, though. They were using Rock, Paper, Scissor as a way to study people's behavior when making decisions in “non-cooperative strategic interactions.” They were testing which of two different broad strategies people use: either trying to play truly randomly, or playing in an evolutionary way with strategies shifting depending on the outcome. (It was the latter.)
Still, though, as good as your strategy may be, you're never going to beat this Rock, Paper, Scissor-playing robot. Sorry.