Jump to content

Rock paper scissors

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by Zandperl (talk | contribs) at 17:08, 16 November 2004 (first rework on "variations"). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

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, Ick-Ack-Ock, Janken, Mora, Gawi-Bawi-Bo, JanKenPon or Farkle) 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 a quick Rochambeau. 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.

History

The game originated in Egypt at around 2000 BC and was then passed to Greece and then on to the Romans. In ancient Rome it was named Micatio and playing it was called micare digitis, literally to "flash the fingers". As time passed the name became Mora which is a corruption of the verb micare. It was so common in ancient Rome that there was a proverb to denote an honest person: Dignus est quicum in tenebris mices, which meant: So trustworthy, that one might play Mora with him in the dark. It was so common that micatio was used to settle disputes over merchandise sales in Roman forums. This practice was later banned by Apronius, prefect of the city.

Game play

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!", "Rocks...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 "weapons":

  • Rock (or "stone"): a clenched fist.
  • Paper: 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.

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 ("I'm going to play a rock") 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).

Cheating

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.

Variations

There are multiple variations on Rock, Paper, Scissors of varying popularity and humor content. These fall into two main types: cosmetic and functional variations. Related hand games are treated in a separate section.

Cosmetic variations

Cosmetic variations are changes to the game that do not alter the core concept of the game in any fashion, but only how it looks to observers. Within this category would be the names of symbols and specific gestures used to indicate each of the three symbols, as well as resulting consequences of the game's outcome.

Names of symbols

Another variation involves changing the names of the symbols. Each symbol has its own gesture associated with it.

One of the most popular is called "Cat, Microwave, Tinfoil". Cat beats tinfoil by ripping it up, tinfoil beats microwave by starting a fire, and microwave beats cat by cooking it. This version was created because, to the creators of Cat Microwave Tinfoil, it doesn't make sense that paper beats rock by covering it (as it doesn't damage the rock, while on the other hand it can destroy the paper by tearing it).

Bulldog, Mongoose, Cobra is another variation, with Bulldog beating Mongoose, Mongoose beating Cobra, and Cobra beating Bulldog. This is the only known variation where sound effects are ritualized and crucial - if you fail to make the Cobra's hissing sound, for example, it is powerless against the Bulldog.

Hunter, Gun, Lion has Hunter beating Gun, Gun beats Lion, and Lion beats Hunter.

In Ninja, Cowboy, Lion, Ninja beats Cowboy, Cowboy beats Lion, and Lion beats Ninja.

In Cow, UFO, Microbe, Cow eats Microbe, UFO dissects Cow and Microbe contaminates UFO.

In another scheme, Hero beats Bear, Bear beats Maiden, and Maiden beats Hero. This version is typically played with the entire body; the specific stances vary. One version is called Bear, Housewife, Cowboy. Players begin by standing facing away from each other approximately 1 meter apart, as if preparing for a duel. They count to three, and on "Go", each player jumps 180 degrees into one of three poses. The Bear pose has legs apart and arms up with hands formed into claws with an optional roar sound effect. Bear eats Housewife. The Housewife pose has legs together and arms close to the body in a gesture of surrender with an optional eek sound effect. Housewife marries Cowboy. The Cowboy pose has legs apart with both hands at the hips in the traditional gun signals of thumbs straight up, index fingers pointing forward and other fingers curled, with optional bang sound effect. Cowboy shoots Bear.

Another variation was presented on That 70's 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.

Australians often play the game as "scissors...paper...rock!", with emphasis placed on the word "rock".

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 Brazilians only have two calls to synchronize the play.

Piers Anthony presents a fictional 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.

Muk-Chi-Ba

While traditional Rock-Paper-Scissors (called "Gawi-Bawi-Bo" and pronounced "Kai-Bai-Bo") is popular among Koreans, a popular related game is Muk-Chi-Ba. A unique variant of Muk-Chi-Ba that adds a layer of complexity was reported in New York City, reportedly created by a Korean-American student at Columbia University.

What makes this version unusual is first, that the hand symbols are different (involving poses with both arms); and second, that the game does not end when one player beats another, but rather when a player with the advantage gets the other player to follow this disadvantaged pose with another in which both players are displaying the same one of the three symbols.

This game is addictive because of its sudden reversals and the quick thinking it requires, and because it can be played anywhere with no props.

Yakyu Ken (Strip Janken)

Another variation is "strip rock-paper-scissors:" a Japanese party/drinking game, where every time a player loses, he or she has to remove an article of clothing. This goes on until one of the players is completely naked.

Osaka Janken

Originating in Kansai, Osaka janken follows the chant "Osaka janken, maketara kachi yo" (Osaka janken, the loser is the winner).

"Extreme Rock Paper Scissors"

Another variation is "Extreme rock paper scissors", in which the winner of each game may use their winning hand position to assault the loser. Paper becomes a slap, rock a punch and scissors a poke (usually in the sternum). This adds the extra challenge of trying to get the more painful positions without your opponent realizing it, and the mere brainless fun of legitimately hitting each other.


Functional variations

Functional variations actually change game play, including associated strategies. These include the number of players and number of symbols (either as additional symbols in the circle, or a more complex topology).

Number of players

The game is easily adaptable to more than just two players. This variant works remarkably well, even for large groups. The rules are the same, with the following exceptions:

  • If all three weapon types are played, or only one type of weapon is played, the round is considered to be a draw. A new round begins.
  • If there are only two different weapon types showing between all of the players, then all of the players showing the losing weapon are eliminated.

Odd or Even (2 symbols)

In Odd or Even, one player selects odd or even. The only choice in weapons are "one" (a fist with outstretched thumb) or "two" (a fist with outstretched thumb and forefinger). The values signified by the players are added, with the first player winning on a correct prediction about the result. With a choice between two values (it does not matter that they are 1 and 2, only that they are not both odd or even) the game is balanced, and there is no benefit from making the call. Should you allow three (or any odd number) values to choose from, either odd or even would be a more probable outcome with both players acting randomly. (That is because n choices make n2 possible outcomes. Squares of even numbers are even, squares of odd numbers odd.)

Five object variations

There exists a five-weapon variation called Rock Paper Scissors Spock Lizard, which is carefully crafted so that each weapon defeats exactly two other weapons, and is defeated by exactly two other weapons. Specifically, rock defeats scissors and lizard, paper defeats rock and Spock, scissors defeat paper and lizard, Spock defeats scissors and rock, and lizard defeats Spock and paper. The game can be similarly altered for 7, 9, 11, etc.. As long as there are an odd number of weapons, a balanced game can be created, with each weapon beating half the weapons and losing to half the weapons. The advantage of playing with more weapons is that ties become increasingly unlikely. The disadvantage is that an increasingly complex resolution table must be memorized (as well as any accompanying gestures).

Another version of this is Rock Paper Scissors Fire Water. This is a slightly more nuanced version, and is especially common among the ultimate frisbee community. Fire beats rock, paper, and scissors, but loses to water. Conversely, water defeats fire and loses to everything else. However, a player is restricted to one use of fire in the course of his or her life. Thus, the subject of when to "throw fire" is quite controversial.

The game of Monkey Kombat from Escape From Monkey Island is effectively a five-object variation, with stances (known as Anxious Ape, Bobbing Baboon, Charging Chimp, Drunken Monkey and Gimpy Gibbon) replacing the objects. The trickiest part of this exercise is the learning of the transitions between the stances (achieved by permutations of the four sacred monkey words Ack, Oop, Eek and Chee).

Trumps (3+)

Players often add other "weapons" to the game on an ad-hoc basis, but it is very likely that this will result in an unbalanced game. In particular, four (or any even number) of weapons cannot be made balanced, unless some pairs of weapons result in a draw; there will always be some weapons that will be superior to others. It also loses some of the aesthetic simplicity of the game, which is otherwise one of the simplest possible games of skill.

Dynamite is an example of a trump play. It is expressed as the extended index finger or thumb, defeats only rock, but is defeated by either scissors or paper. Therefore, anything dynamite will beat, paper will beat; and anything dynamite will tie, paper will tie or beat. Given that paper performs better by tying against another paper, it is always better to use paper than to use dynamite, and dynamite is useless. In game theory, it is said that paper has weak dominance over dynamite.

Fire and water are also potential "trumps", and have been used in ultimate frisbee tournaments. Fire will beat any of the standard weapons (rock, paper, scissors), but because of the power its play is restricted to a single use in the player's entire lifetime. Water may be played as many times as one wishes, but will lose to anything except fire.

Another possible addition is that of well to the original three. Well beats both rock and scissors, because when a rock or a pair of scissors are thrown down a well, they'll fall, but loses to paper because when a paper sheet is thrown, it is likely that it will simply float to the side of the well. The use of this new weapon makes for an extremely unbalanced game, since it doubles the chances of winning while retaining the same amount of chances of losing. In principle, this variation makes Rock useless (as Well beats Scissors and loses to Paper just like Rock does, yet Well beats Rock) and replaces it, leaving the players with the same game and different symbols.

Yet another variation includes string, which wraps around both Rock and Paper, but is cut by Scissors. As Well renders Rock useless, this variation renders Paper useless, as String defeats it and interacts with Rock and Scissors the same.

Tournaments

There are Roshambo tournaments held occasionally. The 2003 Molson Canadian Rock Paper Scissors International World Championships held in Toronto, Ontario were widely reported. 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 1/3 of the time randomly. However, a human cannot be truly random, and the skill in the tournament would involve exploiting your opponent's nonrandom throws.

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.

  • Pointing version: In this variant the winner of each round of the game must make a pointing gesture - up, down, left, or right - with the aim of making their opponent look in that direction. If the loser of the initial rock-paper-scissors can avoid looking in that direction they steal the victory. However if they even glance in the pointed direction, they are confirmed as losers.
  • 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 unrelated to the actual game of Rochambeau.
  • In many real-time strategy computer games, there are three types of troops, with each troop type beating one and losing to another. For example, archers beat pikemen, cavalry beat archers and pikemen beat cavalry or, in a modern setting, light armored vehicles beat infantry, tanks beat light armored vehicles and infantry beat tanks. There are also some turn-based strategy games with a similar dominance structure; however, sometimes the troops are replaced with weapons regarding what dominates what.
  • In Magic: The Gathering, the deckbuilding strategies tend to break down into a few major types. Though only an approximation, usually paper-rock-scissors is compared to aggro-control-combo. Since there is a random element, a matchup is not usually a 100% chance of victory for the dominant deck. The optimal strategy can be found using probability, and depends on what you expect other players to do.
  • Pokémon is sometimes compared to a very complex variant of paper-rock-scissors, particularly the trio of starting Pokémon available in all the games, except Pokémon Yellow. Although the overall type chart is likely unbalanced (which in practice doesn't usually matter too much), the three starting Pokémon's types are very balanced, with Grass (dries up Water), Fire (burns Grass), and Water (douses Fire). However, there are similar trios of Pokémon that do not have balanced type relations – Eevee's three stone-evolved forms, Vaporeon, Jolteon and Flareon; the three legendary birds, Articuno, Zapdos and Moltres; and the legendary trio from the Gold, Silver and Crystal versions, which are Suicune, Raikou and Entei. In each case, the Electric-type Pokémon (Jolteon, Zapdos and Raikou) is superior. Note, however, that just as with Magic: The Gathering, a type advantage does not provide a 100% chance of beating your opponent, only an increased chance.
  • Many role-playing games also have an elemental system (usually involved with the magic system) which, while usually less complex, also provides superiority to certain types when used against other types.
  • Eon Games' Darkover board game used a rock-paper-scissors style combat system. The two players would each hide a "power disk", which could be a sword, a keeper, or a starstone. The power disks are revealed simultaneously; sword beats keeper, which beats starstone, which beats sword. Two swords or two keepers would tie, but ties between starstones were resolved through "psychic combat".
  • In Uru Live, the short-lived online component of the computer game Uru: Ages Beyond Myst, explorers could play a D'ni game called "Ahyoheek", which is a sophisticated Rock, Paper, Scissors implementation. This has been re-enabled in Untìl Uru, the new fan-run online service. It is played on a special pentagonal table with electronic scorekeeping and holographic display built in. See D'ni cultural items for more info.
  • Taasen is a chess-like game with a complex capturing move based on Rock Paper Scissors. It is featured in Unicorn Jelly.
  • Trimok is a fast chess-like game based on rock paper scissors. A freeware version is available and actual game boards and pieces have been made (see external links).
  • The Super Famicom puzzle game Ougijanken, similar to Dr. Mario, is branded as a Ranma game, but is essentially based on Rock, Paper, Scissors.
  • In the Looney Labs board game Cosmic Coasters, the two players decide the outcome of battles between spaceships by playing Rock, Paper, Scissors.

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.)

Retrieved from "https://en.wikipedia.org/w/index.php?title=Rock_paper_scissors&oldid=7528259"