title: On linguistic signalling games in improvised theatre
Creators: name: Morrissey, Lochlan
Publisher: name: Griffith University
Year: 2017
Subjects: subject: Linguistics
subject: FOS: Languages and literature
subject: Improvised theatre
subject: Heuristics

description: This thesis offers a game theoretic model of the use of language in improvised theatre. The model views actors as game theoretic agents; that is, rational agents who select certain utterances, and certain interpretations of these utterances, by calculating the utterance or interpretation that will yield the greatest utility. Actors in improvised performance have the difficult task of executing a performance that is convincingly verisimilar to a group of spectators, while simultaneously generating the plot, and the world in which it takes place, called the plot-world. The generation of a plot requires coordinated action, and cooperative planning, which must take place during the performance. Actors must therefore produce utterances that signal their intentions for the trajectory of the plot, but that conceal this information from the audience, for this planning information damages the verisimilitude of the plot. Concealment of this kind is treated in this thesis as a problem of natural language steganography. The study of steganography involves examination of situations in which information is transmitted between certain parties in such a way that the very presence of this information is kept from unwarranted access. The model set out in this thesis is novel for a game theoretic study of natural language insofar as its primary purpose is to be a comprehensively descriptive model of a particular genre of speech, rather than a generalised, predictive model. To this end, it is based on a dataset of two hours of improvised performance. Basing the model on natural language necessitates the addition of numerous formalisms to the standard model that is used in game theoretic studies of natural language. I make two major amendments to the standard model. (1) Discourse Representation Theory is included as the semantic component of the model. This endows the model with an intensional, model theoretic semantics, and one that is able to express the nuanced meanings that are used in the actors’ concealment of information. (2) Conversations are modelled by iterated games. Iterated games are games that are made up of a number of periods, where these periods are repetitions of a specific game. Iterated games allow for the model to take into account various important facets of communication, including most saliently the cumulative effects of information throughout the course of a conversation, and the alteration of player preferences over time. Three major aspects of the generation of improvised performances are attended to. First, frequent strategies that are used to introduce information into the plot-world are identified, and some of the linguistic characteristics of these strategies are described with respect to the game theoretic model. Second, the use of strategies that are meant to guide certain interpretations of the utterances produced in the course of the performance is discussed. Third, the actual strategies that are used to conceal information, and the precise nature of the information that is concealed, are analysed. At the end of each of these discussions, principles that describe the optimality of certain strategies with respect to the functions of those strategies are proposed. These are called heuristics, and by stating optimal means of achieving certain functions of utterances, it is proposed that they capture the norms by which improvising actors select utterances, and by which they interpret them.