why paper and scissors rock

http://www.gametheory.net/News/Items/081.html

This article talks about professional rock paper and scissors competitions and how scissors is regarded as a risky move. I thought it would be interesting to investigate why this is. We learned in class that all 3 are equal and the best strategy is just to completely randomize. However, if you discover a pattern with your opponent and a less likelihood of your opponent playing a certain set, it would be beneficial to use that information to your advantage.

I think this can be applied to most games that we discussed in class. I believe the goalie example we analyzed in class is a good example of an instance in which there is not an equal chance of one act taking place over another, even though the chances at first appear to be equal based on the rules of the game. For example, when the game of goalkeeping is first explained, it seems logical to assume that there is a 50-50 change of the kicker to aim right or left. Likewise, the original assumption would be that the goalie would therefore have a 50-50 change of jumping right or left. However, when the game is analyzed, it becomes clear that the probability of shooting/protecting right/left is not 50/50 because of the tendencies of individuals to shoot one way over another. Thus, it is best for the goalie to protect one side more than the other based on the probability of the kicker kicking one way over another. This, the mixed nash equilibrium of such games can be calculated to determine better strategies for both players.
Similarly, a game of rock-paper-scissors can be observed over a long period of time and similar mixed nash equilibria can be calculated to come up with good strategies for the players. When this is calculated, it is likely that scissors is favored less for one player than the other two options.

I've actually noticed this before, but I've observed that scissors is a disproportionally common first move in normal people playing RPS. The reasons are unclear, but I think it just feels more satisfying to throw the scissors symbol. Consider the alternatives: Paper, which is just the opening of the hand, and rock, with is no change at all (On the 1-2-3 count, your hand is closed). There's no satisfaction of throwing your hand down on 3 just for it to remain in a closed fist. It sounds weird to say so, but throwing scissors just feels better.

In any case, make use of this info in your future RPS endeavors. Make yout first move rock, as subtly uncomfortable as it may be.

First, I thought I'd respond with a link to the Official Strategy Guide for RPS, here it is, http://www.worldrps.com/index.php?option=com_content&task=view&id=136&Itemid=61

This is what I gathered from the advanced RPS topic on the site. Apparently, as Ian suggested above, there are reasons for why there actually may be a "worst" and "best" strategy. As we learned in class, there is a mixed Nash equilibrium for RPS, which is played each of strategies 1/3 of the time. That way, on average, you should be no worse off than your opponent.

As the article stated, scissors is apparently bad for you, what I've read is that playing each strategy "suggests" something about your behavior.

Playing as Rock - Without realizing it, most players think of Rock as a weapon and will fall back on it for protection when other strategies appear to be failing.

Playing as Scissors - In RPS, scissors are often perceived as a clever or crafty throw, a well-planned outflanking maneuver. As such, players are more likely to use scissors when they are confident or winning.

Playing as Paper - As such, some players perceive Paper as a subtle attack, the victory of modern culture over barbarism. Such players may use Paper to assert their superiority and dignity.


This is pretty funny really. Read more here, http://www.worldrps.com/advanced.html

It seems like picking between rock, paper and scissor is deeply psycological.

In terms of cognitives, playing paper and scissor require holding the hand out then expanding the fingers. Strategically, this may be disadvantageous since your opponent can exploit that few millisecond in your action delay, and respond accordingly.

How to Win at Rock-Paper-Scissors

In this article, the author explains a strategy where you deliberately make your play late, just so you can be accused of cheating and that the play will not count no matter the outcome. During this time, you observe his play, and counter it because he will most likely repeat it.

This is a particularly interesting read:

Rock Paper Scissors Strategy

The author performed strategic analysis by having players pre-submit their plays {R: Rock, P: Paper, S: Scissors} on paper, then calculated their odds of winning.

The plays are pre-submitted to reduce emotion factors during gameplay that may affect decisions during the game.

They categorize the sequence of plays into different categories: Heavy Run, Mixed Run, and Straight Run. And discussed how different runs gain advantage over other runs.

Interesting results and definitely worth a read.

Wow, I never thought about it that way, how each play determines the state of the mind. From class, we believe that RPS is just a mixed nash equilibrium problem. With each choice as 1/3. But it seems that the probability for the nash equilibrium isnt just 1/3, but some conditional probability. Maybe when you throw a Scissors is when you have just beaten a Scissors with you rock. Thus the probability of you throwing a scissors is much higher than 1/3 now. But if we are introducing conditional probability into this mixed nash equilibrium game, then making a right decision become harder, as conditions and thought process various between players.