Discourse Markers In Spontaneous Dialogue: A Corpus Based Study Of Japanese And English

A spontaneously spoken, natural Japanese discourse contains many instances of the so-called redundant interjections and of back-channel utterances. These expressions have not hitherto received much attention and few systematic analyses have been made, since they were regarded as useless, spurious expressions. On the basis of the analysis of spoken dialogue corpus, we claim that these utterances have the characteristics of discourse markers, which delimit and define units of discourse. Our corpus consists of task-oriented dialogues conducted both in Jacanese and in English. The analysis of the Japanese c,:rpus shows that about half of the turns are started with these so-called redundant utterances, while the English corpus shows that about 25 % of the turns start with corresponding English expressions. This suggests that at least in the case oi" Japanese, these so-called redundant utterances have much to do with units of discourse, the building blocks of discourse relations, and that they do indeed function as discourse markers. We show that these utterances comprise a welldefined category, characterizable in a regular manner by their prosodic properties. Prosodic patterns of discourse markers occurring in the recorded corpus have been analyzed. Several pitch patterns have been found that characterize the most frequently used Japanese discourse markers. Based on these characteristic pitch patterns, a system of discourse markers can be designed so that a relatively small number of basic forms are shown to give rise to most of the discourse markers, with intonation patterns corresponding to the functions of discourse markers.