Many improvisational actors also work as scripted actors, and "improv" techniques are often taught in standard acting classes. The basic skills of listening, clarity, confidence, and performing instinctively and spontaneously are considered important skills for actors to develop.
Shortform improv consists of short scenes usually constructed from a predetermined game, structure, or idea and driven by an audience suggestion. Many shortform games were first created by Viola Spolin. The shortform improv comedy television series Whose Line Is It Anyway? has familiarized American and British viewers with shortform.
Longform improv performers create shows in which scenes are often interrelated by story, characters, or themes. Longform shows may take the form of an existing type of theatre, for example a full-length play or Broadway-style musical such as Spontaneous Broadway . Longform improvisation is especially performed in Chicago and New York City. Perhaps the best-known, and considered the first, longform structure is the Harold, developed by ImprovOlympic cofounder Del Close. Many such longform structures now exist.
Improvised performance is as old as performance itself. From the 1500s to the 1700s, Commedia dell'arte performers improvised in the streets of Italyand in the 1890s theatrical theorists and directors such as Konstantin Stanislavski and Jacques Copeau, founders of two major streams of acting theory, both heavily utilised improvisation in acting training and rehearsal.
While some people credit Dudley Riggs as the first vaudevillian to use audience suggestions to create improvised sketches, modern theatrical improvisation is generally accepted to have taken form in the classroom with the theatre games of Viola Spolin in the 1940s and Keith Johnstone in the 1950s. These rehearsal-room activities evolved quickly to an independent artform worthy of presentation before a paying audience.
Viola Spolin can probably be considered the American Grandmother of Improv. She influenced the first generation of Improv at The Compass Players in Chicago, which led to The Second City. Her son, Paul Sills, along with David Shepherd, started The Compass Players and Second City. They were among the first organised troupes in Chicago, Illinois and from their success, the modern Chicago improvisational comedy movement was spawned.
Much of the current "rules" of comedic improv were first formalized in Chicago in the late 1950s and early 1960s, initially among The Compass Players troupe. From most accounts Elaine May was central to this intellectual effort. Mike Nichols, Ted Flicker, and Del Close were her most frequent collaborators in this regard. When Second City opened its doors on December 16th, 1959, Viola Spolin began training new improvisers through a series of classes and exercises which became the cornerstone of modern improv training. By the mid 1960s, Viola's classes were handed over to her protégé, Jo Forsberg who further developed Viola's methods into a one-year course, which eventually became Players Workshop, the first official school of improvisation in the country. During this time Jo Forsberg trained many of the performers who went on to star on Second City stage.
Simultaneously, Keith Johnstone's group The Theatre Machine, which originated in London, was touring Europe. This work gave birth to Theatresports, at first secretly in Keith's workshops, and eventually in public when Keith moved to Canada. Toronto has been home to a rich improv tradition.
In 1984 Dick Chudnow (Kentucky Fried Theater) founded ComedySportz in Milwaukee, WI. Expansion began with the addition of ComedySportz-Madison (WI), in 1985. The first Comedy League of America National Tournament was held in 1988, with 10 teams participating. The league is now known as World Comedy League and boasts a roster of 19 international cities.
In San Francisco, The Committee theater was active during the 1960s.
Modern political improvisation's roots include Jerzy Grotowski's work in Poland during the late 1950s and early 1960s, Peter Brook's "happenings" in England during the late 1960s, Augusto Boal's "Forum Theatre" in South America in the early 1970s, and San Fransico's The Diggers' work in the 1960s. Some of this work led to pure improvisational performance styles, while others simply added to the theatrical vocabulary and were, on the whole, avant garde experiments.
Joan Littlewood, the English actress and director who was active from the 1930s to 1970s, made extensive use of improv in developing plays for performance. However she was successfully prosecuted twice for allowing her actors to improvise in performance. Until 1968, British law required scripts to be approved by the Lord Chamberlain's Office. The department also sent inspectors to some performances to check that the approved script was complied with exactly.
Many silent filmmakers such as Charlie Chaplin and Buster Keaton used improvisation in the making of their films, developing their gags while filming and altering the plot to fit. The Marx Brothers were notorious for deviating from the script they were given, their ad libs often becoming part of the standard routine and making their way into their films.
Improv comedy techniques have also been used in film, television and stand-up comedy, notably the mockumentary films of director Christopher Guest, the recent HBO television show Curb Your Enthusiasm created by Larry David, the UK Channel 4 and ABC television series Whose Line Is It Anyway, Nick Cannon's improv comedy show Wild 'N Out, and most recently, Thank God You're Here. In Canada, the long-running series Train 48 was improvised from scripts which contained a minimal outline of each scene.
In the field of the Psychology of Consciousness, Eberhard Scheiffele explored the altered state of consciousness experienced by actors and improvisers in his scholarly paper: Acting: an altered state of consciousness According to G. WIlliam Farthing in "The Psychology of Consciousness"(see comparative study), actors (in performance, drama classes, or in psychodrama) routinely enter into an altered state of consciousness (ASC). Acting is seen as altering most of the 14 dimensions of changed subjective experience which characterise ASCs according to Farthing, namely: attention, perception, imagery and fantasy, inner speech, memory, higher-level thought processes, meaning or significance of experiences, time experience, emotional feeling and expression, level of arousal, self-control, suggestibility, body image, and sense of personal identity.
Improvisational theatre allows an interactive relationship with the audience. Improv groups frequently solicit suggestions from the audience as a source of inspiration, a way of getting the audience involved, and as a means of proving that the performance is not scripted. That charge is sometimes aimed at the masters of the art, whose performances can seem so detailed that viewers may suspect the scenes were planned.
In order for an improvised scene to be successful, the actors involved must work together responsively to define the parameters and action of the scene, in a process of co-creation. With each spoken word or action in the scene, an actor makes an offer, meaning that he or she defines some element of the reality of the scene. This might include giving another character a name, identifying a relationship, location, or using mime to define the physical environment. These activities are also known as endowment. It is the responsibility of the other actors to accept the offers that their fellow performers make; to not do so is known as blocking, negation, or denial, which usually prevents the scene from developing. Some performers may deliberately block (or otherwise break out of character) for comedic effect -- this is known as gagging -- but this generally prevents the scene from advancing and is frowned upon by many improvisers. Accepting an offer is usually accompanied by adding a new offer, often building on the earlier one; this is a process improvisers refer to as "Yes, And..." and is considered the cornerstone of improvisational technique. Every new piece of information added helps the actors to refine their characters and progress the action of the scene.
The unscripted nature of improv also implies no predetermined knowledge about the props that might be useful in a scene. Improv companies may have at their disposal some number of readily accessible props that can be called upon at a moment's notice, but many improvisers eschew props in favor of the infinite possibilities available through mime. In improv, this is more commonly known as 'space object work' or 'space work', not 'mime'. And the props and locations created by this technique, as 'space objects'. As with all improv offers, actors are encouraged to respect the validity and continuity of the imaginary environment defined by themselves and their fellow performers; this means, for example, taking care not to walk through the table or "miraculously" survive multiple bullet wounds from another improviser's gun.
Because improv actors may be required to play a variety of roles without preparation, they need to be able to construct characters quickly with physicality, gestures, accents, voice changes, or other techniques as demanded by the situation. The actor may be called upon to play a character of a different age or sex. Character motivations are an important part of successful improv scenes, and improv actors must therefore attempt to act according to the objectives that they believe their character seeks.
Many theatre troupes are devoted to staging improvisational performances and growing the improv community through their training centres. One of the most widespread is the international organization Theatresports, which was founded by Keith Johnstone, an English director who wrote what many consider to be the seminal work on the relationship between status, story telling and improvisational acting, Impro. There are also many independent companies around the world; a non-exhaustive but lengthy list is available here In addition to for-profit theatre troupes, there are several college-based improv groups in the United States that are becoming popularized as a result of programs such as Whose Line is it Anyway?.
In Europe the special contribution to the theatre of the abstract, the surreal, the irrational and the subconscious have been part of the stage tradition for centuries. From the 1990s onwards a growing number of European improv groups have been set up specifically to explore the possibilities offered by the use of the abstract in improvised performance, including dance, movement, sound, music, mask work, lighting, and so on. These groups are not especially interested in comedy, either as a technique or as an effect, but rather in expanding the improv genre so as to incorporate techniques and approaches that have long been a legitimate part of European theatre.
Some key figures in the development of improvisational theatre are Avery Schreiber, Viola Spolin and her son Paul Sills, founder of Chicago's famed Second City troupe and originator of Theater Games, and Del Close, founder of ImprovOlympic (along with Charna Halpern) and creator of the longform improv known as The Harold. Other luminaries include Keith Johnstone, the British teacher and writer–author of Impro, who founded the Theatre Machine and whose teachings form the foundation of the popular shortform Theatresports format, and Dick Chudnow, founder of ComedySportz which evolved its family-friendly show format from Johnstone's Theatersports.
In the late 1990s, Matt Besser, Matt Walsh, Ian Roberts, and Amy Poehler founded the Upright Citizens Brigade Theater in New York and later they founded one in Los Angeles. The two theatres host a large improv school.
David Shepherd, with Paul Sills, founded the The Compass Players in Chicago. Shepherd was intent on developing a true "people's Theatre", and hoped to bring political drama to the stockyards. The Compass went on to play in numerous forms and companies, in a number of cities including NY and Hyannis, after the founding of The Second City. A number of Compass members were also founding members of The Second City. In the 1970s, Shepherd began experimenting with group-created videos. He is the author of "That Movie In Your Head", about these efforts. See Coleman, Janet, The Compass: The Improvisational Theatre that Revolutionized American Comedy Chicago, University Of Chicago Press; Reprint edition (November 1, 1991)