Intentlonallty and Human Conversations

This paper analyzes principles of human conversation based on the conversational goals of the participants. Several conversational rules are proposed that seem crucial to the process of interpreting and generating conversations. These rules, as well as other aspects of the conversation process, are embodied in MICS, a computer program that generates one side of a conversation. The process model underlying MICS, and some illustrative output, are presented. I) Formulating rules about human conversations. This paper is an empirical approach to understanding the processes that underlie human conversations. Since the task of codifying all the knowledge required for modeling human discourse is monumental, we confine our approach to formulating rules about the conversational intent of utterances in the course of a dialog. This approach leads us to investigate the effects of shared assumptions and knowledge between the speakers, the social and interpersonal relations of the speakers, and the inferences that must be made by both speakers in a conversation. We take a different approach to analyzing conversations than other research efforts, such as those adopting the speech-acts paradigm (Mann et al [1977]) or investigating task-specific dialogs (Grosz [1977])o in the hope that our new perspective will shed some light on otherwise obscure or neglected aspects of human discourse. Consider the following conversation fragment between Bill and John, two college students sharing an apartment: I) JOHN: Hi, what's new, Bill? BILL: l'm going to visit my folks tonight. We can analyze Bill's utterance in Conversation Fragment (I) in terms of its immediate meaning, that is, a representation of Bill's utterance in Conceptual Dependency or some other meaning representation. This, however, is a very incomplete analysis of what Bill said. Why did Bill say that he was visiting his folks? Bill could just as easily have said, "I'm going to brush my teeth tonight." This utterance, however, doesn't answer John's question; brushing one"s teeth is not "something new". Therefore, we could propose a rather simple conversational rule: RULE I : If a question is asked in the course of a conversation, the other participant should answer this question. Rule I, however, is a little too naive. Suppose Bill's answer was: "There are a few more microns of dust on the windowsill than the last time you asked me that question." This is indeed "something new", but we would think of Bill as a wise guy for answering the question literally rather than addressing what John "must have meant". What did John really mean? John must have been looking for something out of the ordinary and of some intrinsic importance. Let us propose a new rule to incorporate this principle: RULE 2: In the formulation of an answer, the speaker should address the true significance of the question, not just its literal meaning. What is the true significance of a question? In Conversation Fragment (I), Bill might have answered: "The J-particle angular momentum of +3/2 was confirmed today." John, a literature major who does not understand Physics, may not be inclined to continue the conversation. Therefore, Bill's answer is not what was called for, unless Bill intentionally wanted to end the conversation. This example suggests that Bill missed something in establishing the true significance of John's question. John did, indeed, explicitly ask to hear something new; implicitly he meant something important and out of the ordinary. The J-particle answer conforms to these requirements, but it is still an inappropriate response. Therefore, the true significance of John's answer must include John's conversational goal. Why did John ask "What's new"? The answer is, obviously, to start a conversation with Bill. Bill, being aware of this conversational goal, needs to choose an answer that attempts to initiate conversation. That is, Bill should choose a topic of conversation that John can talk about and that John may be interested in. Conversational Rule (3) summarizes this discussion: RULE 3: In introducing a new topic of conversation, the topic should be chosen so that both speakers have some knowledge and interest in its discussion. The process of understanding the conversational import of an utterance may be conceptually divided into two primary subprocesses: I) determine the conversational goal of the utterance, and 2) establish the real, often implicit, meaning of the utterance. Lehnert [1977] analyzes the process of establishing the real meaning of questions. Our analysis focuses on the conversational goals of the participants and the establishment of a shared knowledge base between the participants. It is this shared cultural, personal, and factual knowledge that the conversational participants leave implicit in each commtmication. To illustrate this fact, consider Conversational Fragment (2): 2) JOHN: Do you want to go out and try the bar at Monument Square? BILL: I'm going to visit my folks tonight. Real significance of Bill's utterance: i) No, I do not want to go to the M~nument Square bar. ii) My reason for not wanting to go is that I made a previous commitment, and I cannot be in two places at once tonight.