Rock, Paper, Scissors

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Rock, Paper, Scissors chart

Rock, Paper, Scissors (sometimes with the elements in its name permuted and/or Rock replaced with Stone and/or Paper with Cloth, but also known as Roshambo, Rochambeau, Row-Sham-Bow, Ick-Ack-Ock, Janken, Mora, Morra Cinese, Gawi-Bawi-Bo, JanKenPon, Ca-Chi-Pun, Farkle, Ken Ken Pa, or Kai Bai Bo) is a popular hand game most often played by children. It is often used 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, including ultimate frisbee and university debating, 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

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

Two players each make a fist. They count together "1 ... 2 ... 3 ... Go!", "Rock ... Paper ... Scissors ... Shoot!", "Rock ... Paper ... Scissors!", 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 blunts Scissors (rock wins)
  2. Scissors cuts Paper (scissors win)
  3. Paper covers Rock (paper wins)

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

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

Australians often play the game as "scissors, paper, rock!" or "paper, scissors, rock!", with emphasis placed on the word "rock", or as "hammer, scissors, paper!", with similar emphasis. The throw is made on the final word (either rock or paper) so that players only have two calls to synchronize the play.

Due to the influence of the Japanese-Brazilians, Brazilians prime the game as "jan ... ken ... po!", with emphasis placed on the "po". The throw is made as "po" is called, so that as with the Australian variation, only two calls are made before the play.

In Taiwan, there is commonly no priming. Both players simultaneously throw the hands after a count of three, with no hand-bouncing. This is often confusing to visitors—seeing that the fist-bouncing can be interpreted as rock, most Taiwanese start with paper when playing foreigners.


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 your 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 Roshambo 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."


One of the first tricks learned by a Roshambo novice is to hold back a throw of paper until the last possible moment to dupe an opponent into believing that you may actually be throwing a rock. This allows you the extra few milliseconds for fine-tuning your approach and delivery. Both paper and scissors also have this ability; however, unless you are employing a "double-back" strategy, cloaking a paper throw is likely to draw an instinctive paper from your opponent.

The opening ritual before the actual throws are made ("1 ... 2 ... 3 ... Go!"), 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.


See Rock, Paper, Scissors variations

Math and non-transitivity

Rochambeau 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 Rochambeau: 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, Rochambeau could be called "antitransitive" because if A strictly defeats B, and B strictly defeats C, A necessarily loses against C.


There are Roshambo tournaments held occasionally. Some of the Roshambo websites spoof comparable sites for other games. Real Roshambo 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.

WRPS International World Championships

Starting in 2002 the World Rock Paper Scissors Society (WRPS) standardized a set of rules for international play and has overseen annual International World Championships as well as many regional and national events throughout the year. These championships have been widely attended by players from around the world and have attracted widespread international media attention. WRPS events are noted for their large cash prizes, elaborate staging, and colourful competitors.

WRPS International World Championship Results since 2002

YearHost City Champion Gender Nationality
2002 Toronto, OntarioPete Lovering Male Canadian
2003 Toronto, Ontario Rob KruegerMale Canadian
2004 Toronto, Ontario Lee RammageMale Canadian
2005 TBD

Since 2004 the championships have also been broadcast on the US television network Fox Sports Net.


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.

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 somehow renamed it Paper. These facts suggest Americans imported Rock, Paper, Scissors from Japan in the 19th century.

Pop culture trivia

  • A cosmetic variation was presented on That '70s Show: Foot, Cockroach, Nuclear Bomb. Foot beats cockroach by smashing it, nuclear bomb beats foot by blowing it up, cockroach beats nuclear bomb by surviving the blast.
  • Piers Anthony presents another cosmetic variation of this game as a plot device in his fantasy series Xanth called Fire, Water, Sand. There are two different schools of thought on how the elements interact. Mermaids believe that Water quenches Fire, Fire melts Sand, and Sand covers water. Dragons believe that Fire evaporates Water, Water dilutes Sand, and Sand puts out Fire. This misunderstanding is the cause of a long-standing feud between the two clans.
  • In the TV series South Park, Cartman and his friends play the game "I'll Rochambeau you for it", by kicking the opponent in the crotch. The first one to fall over loses the game. This of course means the first person to go is usually the winner. This is a way of choosing, and it's called Rochambeau, yet it is important to note that game play is obviously unrelated to the actual game of Rock, Paper, Scissors as described here.
KRAMER & MICKEY: Rock, paper, scissors match.
MICKEY: All right, rock beats paper!
(Mickey smacks Kramer's hand for losing)
KRAMER: I thought paper covered rock?
MICKEY: Nah, rock flies right through paper.
KRAMER: What beats rock?
MICKEY: (looks at hand) Nothing beats rock.
KRAMER: All right, come on.
KRAMER & MICKEY: Rock, paper, scissors match.
This pattern then continues for some time.
LISA: Look, there's only one way to settle this. Rock-paper-scissors.
LISA'S BRAIN: Poor predictable Bart. Always takes 'rock'.
BART'S BRAIN: Good ol' 'rock'. Nuthin' beats that!
BART: Rock!
LISA: Paper.
BART: D'oh!


  • 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)

External links

es:Janken fr:Papier-Caillou-Ciseaux ko:가위 바위 보 he:אבן נייר ומספריים ja:じゃんけん nl:Steen schaar papier


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