An Empirical Model of Acknowledgement for Spoken-Language Systems

We reene and extend prior views of the description , purposes, and contexts-of-use of acknowledgment acts through empirical examination of the use of acknowledgments in task-based conversation. We distinguish three broad classes of acknowledgments (other!ackn, self!other!ackn, and self+ackn) and present a catalogue of 13 patterns within these classes that account for the spe-ciic uses of acknowledgment in the corpus. 1 MOTIVATION This study is motivated by the need for better dialogue models in spoken-language systems (SLSs). Dialogue models contribute directly to the interaction by providing inter-utterance coherence. Fluent understanding and use of acknowledgments should improve spoken-language systems in at least the following ways: Preventing miscommunication. Acknowledgments are an important device for establishing mutual knowledge and signaling comprehension. Early detection and correction of cases of mis-communication and misunderstanding should prevent failure that would otherwise have been even more catastrophic. Improved naturalness. Acknowledgments are a prominent feature of human-human dialogue. Supporting the use of acknowledgments for both the system and the user will emphasize the \nat-uralness" of interfaces and improve their utility. Dialogue control. Humans cope with dialogue control (e.g., turn-taking) with seemingly little or no eeort. Acknowledgments form an intricate relationship with dialogue control mechanisms. Understanding these control mechanisms is central to the development and success of spoken language systems in order to \track" dialogues and determine appropriate system actions. Improved recognition. To the extent that a dialogue model can narrow the range of possible contexts for interpretation of a user's utterance, a spoken-language system's speech recognition performance will be improved (Young et al., 1989). We seek to reene and extend prior views of the description, purposes, and contexts-of-use of acknowledgment acts through empirical examination of the use of acknowledgments in task-based conversation. In particular, we seek to describe systematically (1) the communicative value of an acknowledgment and (2) the circumstances of its use. The scope of our inquiry involves spoken interaction. We present a catalogue of types of acknowledgment. This catalogue is based on a process model of acknowledgment that explains instances of these acts in a corpus of task-based conversations. 2 RELATED WORK Clark and Schaefer (1989) suggested that acknowledgments are an important component of a larger framework through which communicating parties provide evidence of understanding. Conversants have a range of means, which vary with respect to strength, for indicating acceptance of a presentation. These include continued attention, initiation of the next relevant contribution, acknowledgment , demonstration. and display. …