Modelling Turn-taking in a Simulation of Small Group Discussion

Abstract

The organization of taking turns at talk is an important part of any verbal interaction such as conversation, particularly in groups. Sociologists and psycholinguists have been studying turn-taking in conversation through empirical and statistical analysis, and identified some systematics in it. But to my knowledge no detailed computational modelling of verbal turn-taking has yet been attempted. This thesis describes one such attempt, for a simulation of small group discussion— that is, engaged conversation in groups of up to seven participants, which researchers have found to be much like two-person dialogues with overhearers. The group discussion is simulated by a simple multi-agent framework with a blackboard architecture, where each agent represents a participant in the discussion and the blackboard is their channel of communication, or ‘environment’ of the discussion. Agents are modelled with just a set of probabilistic parameters that give their likelihood of doing the various turn-taking decisions in the simulation: when to talk, when to continue talking, when to interrupt, when to give feedback (“uh huh”), and so on. The simulation, therefore, consists of coordinating a one-at-a-time talk (symbolic talk) with speaker transitions, hesitation, yielding or keeping the floor, and managing simultaneous talk which occurs mostly around speaker transitions. The turn-taking modelling considers whether participants are talking or not, and when they reach points of possible completion in their utterances that correspond to the places of transition-relevance, TRPs, where others could start to speak in attempts to take a new turn of talk. The agent behaviours (acts), their internal states and procedures are then described. The model is expanded with elaborate procedures for the resolution of simultaneous talk, for speaking hesitations and their potential interruption, and for the constraints of the different ‘sorts’ of utterance with respect to turn-taking: whether the TRP is free, or the speaker has selected someone to speak next, has encouraged anyone to speak, or has indicated the course of an extended multi-utterance turn at talk as in sentence beginnings like “first of all,” or “let me tell you something:. . . ”. The model and extensions are then comprehensively analysed through a series of large quantitative evaluations computing various aggregate statistics such as: the total times of single talk, multiple talk and silences; total occurrences of utterances, silences, simultaneous talk, multiple starts, middle-of-utterance attempts at talking, false-starts, abandoned utterances (interrupted by others), and more.