Cues and control in Expert-Client Dialogues

Cues and control in Expert-Client Dialogues Steve Whittaker & Phil Stenton Hewlett-Packard Laboratories Filton Road, Bristol BSI2 6QZ, UK. email: sjw~hplb.csnet April 18, 1988 Abstract We conducted an empirical analysis into the relation between control and discourse struc- ture. We applied control criteria to four di- alognes and identified 3 levels of discourse structure. We investigated the mechanism for changing control between these structures and found that utterance type and not cue words predicted shifts of control. Participants used certain types of signals when discourse goals were proceeding successfully but resorted to interruptions when they were not. 1 Introduction A number of researchers have shown that there is organisation in discourse above the level of the individual utterance (5, 8, 9, 10), The cur- rent exploratory study uses control as a pa- rameter for identifying these higher level struc- tures. We then go on to address how conversa- tional participants co-ordinate moves between these higher level units, in particular looking at the ways they use to signal the beginning and end of such high level units. Previous research has identified three means by which speakers signal information about discourse structure to listeners: Cue words and phrases (5, 10); Intonation (7); Pronomi- nalisation (6, 2). In the cue words approach, Reichman'(10) has claimed that phrases like "because", "so", and "but" offer explicit in- formation to listeners about how the speaker's current contribution to the discourse relates to what has gone previously. For example a speaker might use the expression "so" to signal that s/he is about to conclude what s/he has just said. Grosz and Sidner (5) relate the use of such phrases to changes in attentional state. An example would be that "and" or "but" sig- nal to the listener that a new topic and set of referents is being introduced whereas "any- way" and "in any case" indicate a return to a previous topic and referent set. A second in- direct way of signalling discourse structure is intonation. Hirschberg and Pierrehumbert (7) showed that intonational contour is closely re- lated to discourse segmentation with new top- ics being signalled by changes in intonational contour. A final more indirect cue to discourse structure is the speaker's choice of referring ex- pressions and grammatical structure. A num- ber of researchers (4, 2, 6, 10) have given ac- counts of how these relate to the continuing, retaining or shifting of focus. The above approaches have concentrated on particular surface linguistic phenomena and then investigated what a putative cue serves to signal in a number of dialogues. The problem 123 with this approach is that the cue may only be an infrequent indicator of a particular type of shift. If we want to construct a general theory of discourse than we want to know about the whole range of cues serving this function. This study therefore takes a different approach. We begin by identifying all shifts of control in the dialogue and then look at how each shift was signalled by the speakers. …

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