Grammatical and Ungrammatical Structures in User-Adviser Dialogues= Evidence for Sufficiency of Restricted Languages in Natural Language Interfaces to Advisory Systems

User-adviser dialogues were collected in a typed Wizard-of-Oz study ("man-behind-the-curtain study"). Thirty-two users had to solve simple statistics problems using an unfamiliar statistical package. Users received help on how to use the statistical package by typing utterances to what they believed was a computerized adviser. The observed limited set of users' grammatical and ungrammatical forms demonstrates the sufficiency of a very restricted grammar of English for a natural language interface to an advisory system. The users' language shares many features of spoken face-to-face language or of language generated under real-time production constraints (i.e., very simple forms of utterances). Yet, users also appeared to believe that the natural language interface could not handle fragmentary or informal language and users planned or edited their language to be more like formal written language (i.e., very infrequent fragments and phaties). Finally, users also appeared to believe in poor shared context between users and computerized advisers and referred to objects and events using complex nominals instead of faster-to-type pronouns.