What can I say?: Evaluating a spoken language interface to email

This paper presents experimental results comparing two different designs for a spoken language interface to entail. We compare a mixed-initiative dialogue style, in which users can flexibly control the dialogue, to a system-iuitiative dialogue style, in which the system controls the dialogue. Our results show that even though the mixed-initiative system is more eflicient, as measured by number of turns, or elapsed time to complete a set of email tasks, users prefer the system-initiative interface. We posit that these preferences arise from the fact that the system initiative inter&e is easier to learn and more predictable