The role of the user in designing natural language dialogue interfaces by Paul Mc Kevitt Department of Computer Science University of Exeter Exeter EX4 4PT, United Kingdom E-mail: JANET: pmc@ac.uk.exeter.cs There are various means by which people express their intentions in natural language dialogue. Any useful computer program which is meant to interact with a user through natural language dialogue better have mechanisms for recognising expressed intention, the different forms in which it comes, and the relationships between those forms. If this is not the case the program will appear irrational and the user will become frustrated. As a step in the direction of determining what expressed intent is, data from written/interactive dialogues between UNIX users and a simulated natural-language help system has been analysed. From initial results it is argued that the recognition of expressed intention has implications for (1) the generation of rational answers, (2) the modeling of users, (3) information retrieval, and (4) the processing of natural language itself. It is believed that one of the major reasons for the failure of natural language interfaces of the past has not only been the lack of the recognition of expressed intent but also the lack of data collection from users.