These effects can vary from hormonal to cognitive health that can impact quality of life and performance

Improvisation

Some classical forms of acting involve a substantial element of improvised performance. Most notable is its use by the troupes of the commedia dell'arte, a form of masked comedy that originated in Italy.

Improvisation as an approach to acting formed an important part of the Russian theatre practitioner Konstantin Stanislavski's 'system' of actor training, which he developed from the 1910s onwards. Late in 1910, the playwright Maxim Gorky invited Stanislavski to join him in Capri, where they discussed training and Stanislavski's emerging "grammar" of acting. Inspired by a popular theatre performance in Naples that utilised the techniques of the commedia dell'arte, Gorky suggested that they form a company, modelled on the medieval strolling players, in which a playwright and group of young actors would devise new plays together by means of improvisation. Stanislavski would develop this use of improvisation in his work with his First Studio of the Moscow Art Theatre. Stanislavski's use was extended further in the approaches to acting developed by his students, Michael Chekhov and Maria Knebel.

In the United Kingdom, the use of improvisation was pioneered by Joan Littlewood from the 1930s onwards and, later, by Keith Johnstone and Clive Barker. In the United States, it was promoted by Viola Spolin, after working with Neva Boyd at a Hull House in Chicago, Illinois (Spolin was Boyd's student from 1924 to 1927). Like the British practitioners, Spolin felt that playing games was a useful means of training actors and helped to improve an actor's performance. With improvisation, she argued, people may find expressive freedom, since they do not know how an improvised situation will turn out. Improvisation demands an open mind in order to maintain spontaneity, rather than pre-planning a response. A character is created by the actor, often without reference to a dramatic text, and a drama is developed out of the spontaneous interactions with other actors. This approach to creating new drama has been developed most substantially by the British filmmaker Mike Leigh, in films such as Secrets & Lies (1996), Vera Drake (2004), Another Year (2010), and Mr. Turner (2014).

Improvisation is also used to cover up if an actor or actress makes a mistake.

Physiological effects

Acting in front of an audience many times can cause "stage fright", a form of stress in which someone becomes anxious in front of an audience. This is common among actors, especially new actors, and can cause symptoms such as increased heart rate, increased blood pressure, and sweating.In a 2017 study on American university students, actors of various experience levels all showed similarly elevated heart rates throughout their performances; this agrees with previous studies on professional and amateur actors' heart rates. While all actors experienced stress, causing elevated heart rate, the more experienced actors displayed less heart rate variability than the less experienced actors in the same play. The more experienced actors experienced less stress while performing, and therefore had a smaller degree of variability than the less experienced, more stressed actors. The more experienced an actor is, the more stable their heart rate will be while performing, but will still experience elevated heart rates.

Semiotics

The semiotics of acting involves a study of the ways in which aspects of a performance come to operate for its audience as signs. This process largely involves the production of meaning, whereby elements of an actor's performance acquire significance, both within the broader context of the dramatic action and in the relations each establishes with the real world.

Following the ideas proposed by the Surrealist theorist Antonin Artaud, however, it may also be possible to understand communication with an audience that occurs 'beneath' significance and meaning (which the semiotician Félix Guattari described as a process involving the transmission of "a-signifying signs"). In his The Theatre and its Double (1938), Artaud compared this interaction to the way in which a snake charmer communicates with a snake, a process which he identified as "mimesis"—the same term that Aristotle in his Poetics (c. 335 BCE) used to describe the mode in which drama communicates its story, by virtue of its embodiment by the actor enacting it, as distinct from "diegesis", or the way in which a narrator may describe it. These "vibrations" passing from the actor to the audience may not necessarily precipitate into significant elements as such (that is, consciously perceived "meanings"), but rather may operate by means of the circulation of "affects".

The approach to acting adopted by other theatre practitioners involve varying degrees of concern with the semiotics of acting. Konstantin Stanislavski, for example, addresses the ways in which an actor, building on what he calls the "experiencing" of a role, should also shape and adjust a performance in order to support the overall significance of the drama—a process that he calls establishing the "perspective of the role". The semiotics of acting plays a far more central role in Bertolt Brecht's epic theatre, in which an actor is concerned to bring out clearly the socio historical significance of behaviour and action by means of specific performance choices—a process that he describes as establishing the "not/but" element in a performed physical "gestus" within context of the play's overal "Fabel". Eugenio Barba argues that actors ought not to concern themselves with the significance of their performance behaviour; this aspect is the responsibility, he claims, of the director, who weaves the signifying elements of an actor's performance into the director's dramaturgical "montage".

The theatre semiotician Patrice Pavis, alluding to the contrast between Stanislavski's 'system' and Brecht's demonstrating performer—and, beyond that, to Denis Diderot's foundational essay on the art of acting, Paradox of the Actor (c. 1770–78)—argues that:

Acting was long seen in terms of the actor's sincerity or hypocrisy—should he believe in what he is saying and be moved by it, or should he distance himself and convey his role in a detached manner? The answer varies according to how one sees the effect to be produced in the audience and the social function of theatre.

Elements of a semiotics of acting include the actor's gestures, facial expressions, intonation and other vocal qualities, rhythm, and the ways in which these aspects of an individual performance relate to the drama and the theatrical event (or film, television programme, or radio broadcast, each of which involves different semiotic systems) considered as a whole. A semiotics of acting recognises that all forms of acting involve conventions and codes by means of which performance behaviour acquires significance—including those approaches, such as Stanislvaski's or the closely related method acting developed in the United States, that offer themselves as "a natural kind of acting that can do without conventions and be received as self-evident and universal." Pavis goes on to argue that:

Any acting is based on a codified system (even if the audience does not see it as such) of behaviour and actions that are considered to be believable and realistic or artificial and theatrical. To advocate the natural, the spontaneous, and the instinctive is only to attempt to produce natural effects, governed by an ideological code that determines, at a particular historical time, and for a given audience, what is natural and believable and what is declamatory and theatrical.

The conventions that govern acting in general are related to structured forms of play, which involve, in each specific experience, "rules of the game." This aspect was first explored by Johan Huizinga (in Homo Ludens, 1938) and Roger Caillois (in Man, Play and Games, 1958). Caillois, for example, distinguishes four aspects of play relevant to acting: mimesis (simulation), agon (conflict or competition), alea (chance), and ilinx (vertigo, or "vertiginous psychological situations" involving the spectator's identification or catharsis). This connection with play as an activity was first proposed by Aristotle in his Poetics, in which he defines the desire to imitate in play as an essential part of being human and our first means of learning as children:

For it is an instinct of human beings, from childhood, to engage in mimesis (indeed, this distinguishes them from other animals: man is the most mimetic of all, and it is through mimesis that he develops his earliest understanding); and equally natural that everyone enjoys mimetic objects. (IV, 1448b)

This connection with play also informed the words used in English (as was the analogous case in many other European languages) for drama: the word "play" or "game" (translating the Anglo-Saxon plèga or Latin ludus) was the standard term used until William Shakespeare's time for a dramatic entertainment—just as its creator was a "play-maker" rather than a "dramatist", the person acting was known as a "player", and, when in the Elizabethan era specific buildings for acting were built, they was known as "play-houses" rather than "theatres."

Resumes and auditions

Actors and actresses need to make a resume when applying for roles. The acting resume is very different from a normal resume; it is generally shorter, with lists instead of paragraphs, and it should have a head shot on the back. Sometimes, a resume also contains a short 30 second to 1 minute reel displaying the actors ability's, so that the casting director can see your previous performances, if any. An actor's resume should list projects they have acted in before such as plays, movies, or shows, as well as special skills and their contact information.Auditioning is the act of performing either a monologue or sides (lines for one character) as sent by the casting director. Auditioning entails showing the actor's skills to present themselves as a different person; it may be as brief as two minutes. For theater auditions it can be longer than two minutes, or they may perform more than one monologue, as each casting director can have different requirements for actors. Actors should go to auditions dressed for the part, to make it easier for the casting director to visualize them as the character. For television or film they will have to undergo more than one audition. Oftentimes actors are called into another audition at the last minute, and are sent the sides either that morning or the night before. Auditioning can be a stressful part of acting, especially if one has not been trained to audition.

Rehearsal

Rehearsal is a process in which actors prepare and practice a performance, exploring the vicissitudes of conflict between characters, testing specific actions in the scene, and finding means to convey a particular sense. Some actors continue to rehearse a scene throughout the run of a show in order to keep the scene fresh in their minds and exciting for the audience.

Audience

A critical audience with evaluative spectators is known to induce stress on actors during performance, (see Bode & Brutten). Being in front of an audience sharing a story will makes the actors intensely vulnerable. Shockingly, an actor will typically rate the quality of their performance higher than their spectators. Heart rates are generally always higher during a performance with an audience when compared to rehearsal, however what's interesting is that this audience also seems to induce a higher quality of performance. Simply put, while public performances cause extremely high stress levels in actors (more so amateur ones), the stress actually improves the performance, supporting the idea of "positive stress in challenging situations"

Heart rate

Depending on what an actor is doing, his or her heart rate will vary. This is the body's way of responding to stress. Prior to a show one will see an increase in heart rate due to anxiety. While performing an actor has an increased sense of exposure which will increase performance anxiety and the associated physiological arousal, such as heart rate. Heart rates increases more during shows compared to rehearsals because of the increased pressure, which is due to the fact that a performance has a potentially greater impact on an actors career. After the show a decrease in the heart rate due to the conclusion of the stress inducing activity can be seen. Often the heart rate will return to normal after the show or performance is done; however, during the applause after the performance there is a rapid spike in heart rate. This can be seen not only in actors but also with public speaking and musicians.

Stress

There is a correlation between heart-rate and stress when actors' are performing in front of an audience. Actors claim that having an audience has no change in their stress level, but as soon as they come on stage their heart-rate rises quickly. A 2017 study done in an American University looking at actors' stress by measuring heart-rate showed individual heart-rates rose right before the performance began for those actors opening. There are many factors that can add to an actors' stress. For example, length of monologues, experience level, and actions done on stage including moving the set. Throughout the performance heart-rate rises the most before an actor is speaking. The stress and thus heart-rate of the actor then drops significantly at the end of a monologue, big action scene, or performance.