This chapter focuses on how people use language, a field of study often called pragmatics, especially on how they use it in discourse, broad but bounded stretches of language activity. Discourses are global joint activities that emerge from an artful and opportunistic series of local joint actions. This chapter describes the traditional view of the actions people perform in using language. Whenever people use language, they are taking actions. But their individual actions are not autonomous. They are parts of joint actions in which the participants are trying to coordinate with each other. The chapter then presents a contrasting view about the way speakers and addressees act jointly in discourse, suggesting that speakers and addressees cannot do without each other; illocutionary acts cannot succeed without coordinated acts of recognition. Speaker's meaning makes no sense without the reciprocal addresses understanding. But people use language to do things with each other. Finally, the chapter explores how the participants in a discourse achieve local and more extended joint projects, and how they coordinate with each other in telling stories.

Spoken language systems for the near future will not handle all of English, but, rather, will be limited to a domain-specific sub-language. Accurate modeling of the sub-language will depend on analysis of domain-specific data. Since no spoken language systems currently have a wide range of users, and since variability across users is expected to be large, we are simulating applications in which a large population of potential users can be sampled. The data resulting from the simulations can be used for system development and for system evaluation. The application discussed here is the air travel domain using the Official Airline Guide (OAG) reformatted in a relational structure.This study assesses the effects of changes in the simulations on the speech and language of the experimental subjects. These results are relevant to both the experimental conditions for data collection and the design of the human interface for spoken language systems. We report here on five experiments: (1) the effect of longer instructions with examples vs. shorter instructions, using our earlier data collection system, (2) a baseline experiment using a functional equivalent of the data collection effort at Texas Instruments (TI), (3) the use of a more specific version of the scenario used in the baseline experiment, (4) the use of a short, simple familiarization scenario before the main scenario, and (5) in addition to the short familiarization scenario, the use of a finite vocabulary with rejection of sentences with extra-lexical items.