Non-sentential responses to requests for information

When faced with requests for information ("Where did you go last night?"), why do speakers make non-sentential replies ("The movies") rather than full sentence replies ("I went to the movies")? We examine the role that pragmatic factors (politeness and formality) and memory factors (the speaker's ability to retrieve the answer to the question) play in determining whether speakers generate a non-sentential reply. Participants answered a series of questions about their lives. Pragmatic factors affected the participants' responses. Speakers instructed to be polite or formal made fewer non-sentential replies than speakers who did not receive specific instructions. Memory retrieval (indexed both by the time required for the participant to begin their response and by the presence of disfluencies at the beginning of the response) did not have a straightforward relationship to the production of non-sentential replies. The effect of response latency and disfluencies depended on whether the participants were told to be polite or formal (or if they were given no instruction at all).