A Computational Model of Incremental Utterance Production in Task-Oriented Dialogues

A Computational Model of Incremental Utterance Production in Task-Oriented Dialogues Kohji Dohsaka NTT Basic Research Laboratories 3-1 Morinosato-wakamiya, Atsugi, Kanagawa, 243-01 Japan dohsaka@at om. brl. ntt. j p Akira Shimazu NTT Basic Research Laboratories 3-1 Morinosato-wakamiya, Atsugi, Kanagawa, 243-01 Japan shimazu@at om. brl. ntt. jp Abstract This paper presents a comtmtational model of incremental utterance produc- tion in task-oriented dialogues. This model incrementally produces utter- antes to propose the solution of a given problem, while simultaneously solving the problem in a stepwise manner. Even when the solution has been partially de- termined, this model starts utterances to satisfy time constraints where pauses in mid-utterance must not exceed a cer- tain length. The results of an analysis of discourse structure in a dialogue cor- pus are presented and the fine structure of discourse that contributes to the in- cremental strategy of utterance produc- tion is described. This model utilizes such a discourse structure to incremen- tally produce utterances constituting a discourse. Pragmatic constraints are ex- ploited to guarantee the relevance of dis- courses, which are evaluated by an utter- ance simulation experiment. 1 Introduction Dialogues occur in real-time and so are suscep- tible to time constraints. For example, dialogue participants must produce utterances under time constraints where pauses in mid-utterance must not exceed a certain length. Moreover, partici- pants are inference-limited (Walker and Rainbow 1994). Due to time constraints and limits in ilffer- ence, dialogue participants cannot help producing utterances incrementally. Incremental utterance production is characterized like this: speakers pro- duce utterances while deliberating what to say~ and refine what they will say while articulating the first part of their utterances. The incremental strategy of utterance produc- tion plays a crucial role in spoken dialogues in two respects. First, it helps speakers to satisfy time constraints on pauses. This is crucial since lengthy pauses imply the transition of a turn from the cur- rent speaker to others. Second, it helps hearers to easily understand utterances since it enables the piecemeal transmission of information. This paper presents a computational model of incremental utterance production in task-oriented dialogues. This model produces utterances to pro- pose the solution of a given problem while simulta- neously solving the problem in a stepwise manner. To satisfy time constraints on pauses, this model starts utterances even when the solution has not been fully determined and refines on the solution during the articulation of utterances. We present the results of an analysis of dis- course structure in a corpus of Japanese task- oriented dialogues and show that the fine struc- ture of discourse prevails in spoken dialogues and the predominant discourse structure contributes to the incrementM strategy. Based on such a dis- course structure, this model incrementally pro- duces utterances constituting a discourse. How- ever, the incremental strategy is subject to gen- erating irrelevant discourses. To guarantee the relevance of discourses, this model utilizes prag- matic constraints and a context model, which are evaluated in an utterance simulation experiment. 2 Related Research Recent studies of human speech production …

Content truncated to 500 words