Rock-Paper-Scissors Robot

How in the world did I not know about this for three years?

Researchers at the University of Tokyo have developed a robot that always wins at rock-paper-scissors. It watches the human player’s hand, figures out which finger position the human is about to deploy, and reacts quickly enough to always win.

EDITED TO ADD (6/13): Seems like this is even older—from 2013.

Posted on June 12, 2019 at 6:22 AM19 Comments


Moke June 12, 2019 6:40 AM

Looking at the slow motion at the end it appears at cheating.
The robot hand always make their move after the human, aka cheating.

Now it’s still good work. Making the reaction time that short might require prediction but the video itself doesn’t show that.

Ian D. P. June 12, 2019 7:09 AM

Technically it is cheating, yet still amazing. Imagine if it were applied to boxing or fencing. It would be able to defend itself against any kind of attack.

Geo June 12, 2019 11:57 AM

I wonder if you could beat it with its own game. Bring down a rock but change it to scissors after a slight delay.

Tatütata June 12, 2019 12:15 PM

I’m not really impressed, the machine merely exploits its speed in tracking a human decision made hundreds of milliseconds earlier. (But I’d be interested in seeing a tennis playing robot. I see that ping-pong is already conquered, but the brains appear to concentrate on the ball rather than the opposing player.)

Back in his day, Claude Shannon built game playing machines based on statistics, in particular tic-tac-toe (where a draw is the standard result). A handful of relays kept together by bailer twine.

On a separate subject, BoJo recently hung up on a fellow buffoon, thinking it was [yet another] prank call. There is a dire need of caller authentication between so-called “VIPs”.

Impossibly Stupid June 12, 2019 2:36 PM

How in the world did I not know about this for three years?

Do you also not know about xkcd? You’re one of today’s lucky 10,000:

That said, the more interesting question is whether or not this is truly “cheating”, or just some actor making full use of their normal abilities. There’s a female runner in the news who has a higher testosterone level than is usually the case for women, and all sorts of machinations are being made to try to keep her from competing. Or what do we make of people who lost their lower legs now using those springy blades to run? Are they only “handicapped” if they’re slower than you, but “cheating” if they’re faster?

Regardless, the security perspective here is to not assume the game you’re playing is exactly the same game someone (or something) else is playing. That’s why, for example, politicians and/or law enforcement demanding that companies give them all sent messages unencrypted will remain laughable. Similarly to this “brute force” attack on R-P-S, I expect that things like locks (both keyed and combination) are mechanisms that would not hold up well to an exhaustive, machine-based attack. I even assume that such things have already been demonstrated, maybe even years ago, too, and I’ve also just not heard about them yet.

David Leppik June 12, 2019 4:01 PM

On Dr. Who back in the 1980s, The Doctor (Tom Baker) taught rock/paper/scissors to a group of Cybermen and used it as an example of why humans are better than machines. If I remember correctly, it was because humans could use psychology to guess the next play, while the Cybermen could only see it as a pure game of chance. The episode’s writers never saw this coming!

No One June 12, 2019 7:06 PM

Wait a second.

News about robots defeating humans is about to become more common–at least for a while.

RealFakeNews June 12, 2019 10:05 PM

It’s cheating.

Any humans successful at consistently defeating it by giving contradictory hints?

Ismar Duderija June 13, 2019 1:12 AM

Do I really want to have a machine capable of interacting with me in the same way other humans can ? Whether I like it or not we seem to be heading in that direction.

Rachel June 13, 2019 9:21 AM

Thanks for the amusing comments! There is a fictional drama series in the UK called ‘Humans’ , based on the original Swedish ‘Real Humans’, about society forced to adapt to the introduction of human identical androids, known as ‘Synths’ who are available for purchase to live in the family home as a maid-nanny, or for performing labour. They are not exactly meta humans but they do have skills surpassing their mortal counterparts in some respects. The drama revolves around the inevitable tensions that arise between the classes of human and synths, particularly as the latter begin to demand they deserve the same rights and treatment as humans. It is gripping, yet all treated with a light hand without getting moralistic or explicit. Definitely of interest to participants here.

Clive Robinson June 13, 2019 6:33 PM

@ Not Irritated Today :), David Leppik,

4th Doctor and Romana

I can’t remember their personal relationship state at the time, but that was mainly a Douglas Adams script. As normal Douglas was not altogether with it and the script was an amalgamation of several story lines and threads for future story lines.

They were interesting and fun times.

@ Rachel,

There is a fictional drama series in the UK called ‘Humans’

I trust you are well? I’m told Humans has it’s moments, I’ve not watched it for various reasons (mainly I’ve given up on it even for news).

However I did inadvertantly see a bit of it being filmed at “Botany Bay” to the north of Broadstairs in Kent, though I did not know it at the time. I was down there up on the cliffs doing a bit of “radio stuff” and there was as often is there filming going on. The rules of the game are “presumed consent” so if you get in shot for what ever reason you can not later say “Oi I want’s paying” or some such. Before people get their videos out looking for me, I am a shy retiring type thus keep out of the way thus I apparently succeeded in not get in any of the shots. But some one who was also doing the “radio stuff” with me later recognised it when watching the series.

For some reason hardly a fortnight goes by when they are not filming something around where I live and it’s easy to spot the signs and the catering vehicles, especially when you are having a quiet cupper with a friend at the local sports arena and they are occupying a big chunk of the coach park and recognisable faces hove into view.

Clive Robinson June 13, 2019 6:44 PM

@ Impossibly Stupid,

Do you also not know about xkcd? You’re one of today’s lucky 10,000:

If you look back on this blog, I was one of those “lucky 10,000” who had not heard about Coke and Mento’s when @Bruce joked about it.

Alyer Babtu June 15, 2019 11:11 AM

Seems appropriate –

The Hives “Walk Idiot Walk”

See the robot walk
See the robot talk
See the robot write up his name on the ballot

He won and now he’s gonna do something about it

See the robot talk
Still you never learned nothing and nothing isn’t over

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