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Rock paper scissors

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For the Catatonia album, see Paper Scissors Stone (album).
Rock, Paper, Scissors chart

Rock, Paper, Scissors (also known by several other names) is a popular hand game most often played by children. It is often used as a selection method in a similar way to coin flipping, Odd or Even, throwing dice or drawing straws to randomly select a person for some purpose, though unlike truly random selections it can be played with skill if the game extends over many sessions, because one can often recognize and exploit the non-random behavior of an opponent.

Various sports (for example, Ultimate) may use Rock, Paper, Scissors to determine which team gets the opening play (rather than a coin toss). Similarly, uncertain calls, or even the whole game in case of rain, may be decided by the game. It is also often used as a method for creating appropriately biased random results in live action role-playing games, as it requires no equipment.

Game play

Each of the three basic hand-signs ( from left to right: rock, paper and scissors ) beats one of the other two.

They (the players) count together "1 ... 2 ... 3 ... Shoot!", "Rock ... Paper ... Scissors ... Shoot!", "Rock ... Paper ... Scissors!", "Scissors... Paper... Stone!", or "Ro ... Sham ... Bo!" while simultaneously bouncing their fists. On "Shoot", "Go", or "Scissors", each player simultaneously changes their fist into one of three hands (or weapons):

  • Rock (or Stone): a clenched fist.
  • Paper (or Cloth): all fingers extended, palm facing downwards, upwards, or sideways (thumb pointing to the sky).
  • Scissors: forefinger and middle finger extended and separated into a "V" shape.

The objective is to defeat the opponent by selecting a weapon which defeats their choice under the following rules:

  1. Rock smashes (or blunts) Scissors (rock wins)
  2. Scissors simply cuts Paper (scissors win)
  3. Paper covers Rock and roughness is covered (paper wins)

If players choose the same weapon, the game is a tie and is played again.

Typically, the short game is repeated so that the person who wins two out of three or three out of five times wins the entire game.


Strategies

Strategy between human players obviously involves using psychology to attempt to predict or influence opponent behavior. It is considered acceptable to use deceptive speech ("Good old Rock, nothing beats that!") to influence one's opponent.

Mathematically optimal play (according to game theory) is a simple matter of selecting randomly, and so the game may be considered trivial in that sense when played in a way that eliminates psychology, as with a computer. But "optimal" in this sense means only "incapable of being defeated more than expected by chance", while it does not imply that the random strategy is best at taking advantage of a suboptimal opponent. In fact, if the opponent is human or a non-random program, it is almost certain that he plays suboptimally and that a modified strategy can exploit that weakness. This is easily demonstrated by Roshambot, a computer program that easily defeats some human players (as does its author Perry Friedman, who won an $800 competition against seven opponents including former world poker champion Phil Hellmuth in August 2001). Poker player Darse Billings of the University of Alberta organizes a computer Rock-Paper-Scissors competition to explore these possibilities, and their application to computer game play in other fields (notably poker, in which exploiting an opponent's non-random behavior is an important part of strategy).

One high-profile strategic opinion came in 2005 from Alice Maclean, age 11. When rival auction houses Christie's and Sotheby's agreed to play rock-paper-scissors to determine the rights to a highly valuable art collection, Maclean's father Nicholas, a Christie's employee, asked her for advice. As later told to reporters, her strategy was summed up thus: "Everybody knows you always start with scissors. Rock is way too obvious, and scissors beats paper." (Christie's won, with scissors)

Cheating

One of the first tricks learned by a Rock-Paper-Scissors novice is to hold back a throw of paper until the last possible moment to dupe an opponent into believing that one may actually be throwing a rock. Both paper and scissors have this ability; however, unless one is employing a "double-back" strategy, cloaking a paper throw is likely to draw an instinctive paper from one's opponent.

The opening ritual before the actual throws are made ("1… 2… Shoot!" or “Rock, paper, scissors, shoot!”), called "priming", is intended to get both players in sync so as to ensure simultaneous delivery of throws. This can be used to an advantage when two players are meeting for the first time, since it is often unclear as to what the priming speed will be. The tendency is to default to the priming speed of the faster player. This allows the faster priming player the luxury of dictating the flow of play and causes their opponent to dedicate more energy to "catching the prime" rather than concentrating on delivering an effective throw.

A common variation on the opening ritual is to have both players hold their hands behind their backs and reveal their already formed throw after the count of three. The intention is to prevent any sort of timing based cheating. This is often seen among live action role-players.

Among children and immature adults, the "bomb" (thrown the same as a rock, except with the thumb sticking straight up rather than hidden. ) is employed as a desperate attempt to thwart one's opponent. Needless to say, this maneuver is illegal, and those who employ this tactic are scorned for cheating. Other variants of this include the finger, volcano, fire, and gun. However, in certain Live-action Role-playing games, the bomb is a legal move used in particular situations, such as the ultimate level of a skill.

Variations

See Rock, Paper, Scissors variations

There are many different variations of Rock, Paper, Scissors which range from simple changes in the names of the objects to increasing the number of players or objects. While interesting, most rule variations suffer from one problem or another, making them less interesting games. Versions of this game are also observed in many different cultures. It is usually known by direct translations of "Rock, Paper, Scissors" although some cultures have slightly different names representing different objects. Minor variation is also observed in the standard game play.

Math and non-transitivity

Rock, Paper, Scissors is also often used as an example of the mathematical concept of non-transitivity. A transitive relation R is one for which a R b and b R c implies a R c. A reflexive, antisymmetric, and transitive relation on a set is known as a partial ordering, from which notions of "greater" and "less" follow. A game option which is "greater" than another is closer to being optimal, but such a notion does not exist in Rock, Paper, Scissors: The relation used to determine which throws defeat which is non-transitive. Rock defeats Scissors, and Scissors defeat Paper, but Rock loses to Paper. In fact, Rock-Paper- Scissors could be called "antitransitive" because if A strictly defeats B, and B strictly defeats C, A necessarily loses against C.

Tournaments

There are Rock-Paper-Scissors tournaments held occasionally. Some of the Rock-Paper-Scissors websites spoof comparable sites for other games. Real Rock-Paper-Scissors tournaments are an interesting psychological exercise. Obviously, the strategy dictated by game theory is to pick each choice one-third of the time randomly. However, a human cannot be truly random, and the skill in the tournament involves inciting and exploiting nonrandom throws from one's opponents. The ability for certain experienced players to consistently reach the finals of high level tournaments is a strong testament to skill influencing the outcome of the game.

In Japan, Janken tournaments are often held on television variety programs, especially between popular actors, and the game is also often used by advertising kiosks as tool for audience participation.

History

Like Go and Mahjong, Rock, Paper, Scissors was invented by the Chinese. According to a book named Wǔzázǔ (五雜俎 or 五雜組) written by Xiè Zhàozhì (謝肇淛) in the late Ming period, warlords of Later Han played a game called shǒushìlìng (手勢令), which is considered to be Rock, Paper, Scissors. Shǒushìlìng can be translated as "hand-command."

There is no record of Rock, Paper, Scissors in the West before they had direct contacts with Asians. Western writers in the late 19th century only mentioned it as an Asian game. The Chinese and Koreans use Cloth along with Rock and Scissors, while the Japanese have adopted Paper.

Jan Ken Pon - Some Historical Data

Pop culture trivia

Main article: [[:List of pop culture references to Rock, Paper, Scissors]]

Because of its widespread use by children and adults, Rock Paper Scissors has received substantial references in popular culture. Seinfeld, The Simpsons, and That 70s Show all poke fun at particular characters' incompetence at understanding the game rules. In other shows, mischeivious characters are often able to "win" the game by deploying new objects which beat all the others and are subsequently able to convince their slow-witted competitor that deploying the new object is a legitimate move. In video games, intransitive relationships (like Rock, Paper, Scissors) often appear either in strategy choices or in weapons' abilities.

Evolutionary strategy

The Common Side-blotched Lizard (Uta stansburiana)'s exhibits a Rock-Paper-Scissors pattern in its mating behaviour evolutionary strategy.

Biologist Barry Sinervo from the University of California, Santa Cruz has discovered a Rock-Paper-Scissors evolutionary strategy in the mating behaviour of the side-blotched lizard species Uta stansburiana. Males have either orange, blue or yellow throats and each type follows a fixed, hereditable mating strategy:

  • Orange-throated males are strongest and do not form strong pair bonds; instead, they fight orange-throated males for their females. Yellow-throated males, however, manage to snatch females away from them for mating.
  • Blue-throated males are middle-sized and form strong pair bonds. While they are outcompeted by orange-throated males, they can defend against yellow-throated ones.
  • Yellow-throated males are smallest, and their coloration mimicks females. Under this disguise, they can approach orange-throated males but not the stronger-bonding blue-throated specimens and mating while the orange-throats are engaged in fights.

The proportion of each male type in a population is similar in the long run, but fluctuates heavily in the short term. For periods of 4-5 years, one strategy predominates, after which it declines in frequency as the strategy that manages to exploit its weakness increases. This corresponds to the stable patern of the game in the replicator dynamics where the dynamical system follows closed orbits around the mixed strategy Nash equilibrium.


References

  • Sogawa, Tsuneo (2000). "Janken". Monthly Sinica, Vol.11, No.5. (Japanese)
  • Culin, Stewart. (1895). Korean Games, With Notes on the Corresponding Games at China and Japan. (evidence of nonexistence of Rock, Paper, Scissors in the West)
  • Gomme, Alice Bertha. (1894, 1898). The traditional games of England, Scotland, and Ireland, 2 vols. (ditto)
  • Opie, Iona and Peter (1969). Children's Games in Street and Playground Oxford University Press, London. (Details some variants on Rock, Paper, Scissors such as 'Man, Earwig, Elephant' in Indonesia, and presents evidence for the existence of 'finger throwing games' in Egypt as early as 2000 B.C.)
  • Alonzo, S.H. and Sinervo, B. (2001). "Mate choice games, context-dependent good genes, and genetic cycles in the side-blotched lizard, Uta stansburiana". Behavioral Ecology Sociobiology Vol.49, pp.176-186
  • Sinervo, B., and Lively, C. (1996). "The Rock-Paper-Scissors Game and the evolution of alternative male strategies". Nature Vol.380, pp.240-243
  • Walker, Douglas & Graham (2004). "The Official Rock Paper Scissors Strategy Guide" Fireside (RPS strategy, tips and culture from the World Rock Paper Scissors Society).

Other names

Sometimes the elements in its name are permuted, or modified to include

  • Cockroach, Foot, Nuclear Explosion - Cockroach beats Nuclear Explosion, Foot beats Cockroach, Nuclear Explosion beats Foot
  • Rock replaced with Stone
  • Paper with Cloth
  • Ca-Chi-Pun
  • Ching-Chong-Cha
  • Ching-Chang-Push
  • Even-Neyar-uMisparayim
  • Gawi-Bawi-Bo
  • Grizzly, Cowboy, Ninja
  • Ick-Ack-Ock
  • Jack en Poy
  • JanKenPon
  • Janken
  • Kai Bai Bo
  • Paper-Rock-Scissors
  • Mora
  • Morra Cinese
  • Rochambeau
  • Roshambo
  • Row-Sham-Bow
  • Schnik Schnak Schnuk
  • Scissors-Paper-Rock
  • Scissors-Paper-Stone
  • Paper Scissors Stone
  • Stein, saks, papir (In Norwegian)
  • Piedra-Papel-Tijeras (In Spanish)
  • Shitou-Jianzi-Bu (Stone-Scissors-Cloth in Mandarin)
  • Papier/Blad-Steen-Schaar (In Dutch)
  • Mouse-Cheese-Cat Mouse eats cheese, cheese distracts cat, cat eats mouse.
  • Bato, Bato, Pick (In Tagalog)

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