Pragmatics In Speech Understanding

The pragmatics component of SPEECHLIS is a process which applies various facts about the speaker, the previous dialogue, and the domain of discourse to interpret utterances and respond appropr iately. For example, an early version of the system operates as a question answerer for the domain of lunar geology. In that domain one is usually not concerned with the particular scientists who investigated the samples, but rather with the samples themselves. Thus verbs which allow agent deletion in the passive voice are usually expressed that way, rather than in the active voice. One says "Which new minerals were discovered in the lunar breccias?" and not "Which new minerals did the investigators discover in the lunar breccias?" In the current travel budget management system we have recognized similar effects of pragmatics in simulated dialogues. For instance, following a supposition, a speaker tyoically asks a question. This question usually concerns future events and is related to the content of the supposition. Another example is that use of the verb "cancel" implies that the speaker believes that the object of "cancel" has previously been entered into the system data base. There is no doubt that pragmatics information can be helpful in certain cases. We are currently exploring the use of a user/task model to generalize and structure the pragmatics rules we have discovered. This model provides a focus on a central issue in pragmatics, the recognition of the speaker's purpose. A person uses a speech system to accomplish some purpose, whether that be to obtain information, to gain assistance in planning and decision making, or to control some process. His purpose is reflected in both the vocabulary and syntax of the language and in the interpretations which are assigned to utterances. An at least implicit recognition of the purpose behind an utterance is necessary for complete speech understanding. Related work by Deutsch [41 has also shown the importance of a model of the user's purpose in understanding spoken dialogue. 461 When a person speaks he is using words to achieve a goal, whether that be to gain information, to threaten, to promise, or to reassure. Recognition of that goal is an essential part of speech understanding, both in determining what was said and in deciding what was meant. The term "pragmatics" is used here to mean the procedure which applies knowledge about the speaker, the previous dialogue, and the domain of discourse to …