The Pragmatics of Referring and the Modality of Communication

This paper presents empirical results comparing spoken and keyboard communication. It is shown that speakers a t tempt to achieve more detailed goals in giving instructions than do users of keyboards. One specific kind of f ine-grained communicative act, a request that the hearer identify the referent of a noun phrase, is shown to dominate spoken instruction-giving discourse, but is nearly absent from keyboard discourse. Most important , these requests are only achieved "indirect ly". through ut terances whose surface forms do not explicitly convey the speakers ' intent. A plan-based theory of communication is shown to uncover the speakers' intentions underlying many cases of indirect identification requests found in the corpus, once an action for re ferent identification has been posited. In so doing, the theory demonstrates how intent (or plan) recognition can be applied in reasoning about the use of a description. As a consequence of this approach, it is shown that the conditions on the planning of successful identification requests account for Sear le ' s conditions on the act of referring. I t is concluded that intent recognition will need to be a central focus for pragmat ics /d iscourse components of future speech understanding systems, and that computat ional linguistics needs to develop formalisms for reasoning about speakers' use of descriptions.