Effects of Shortening Speech Prompts of In-Car Voice User Interfaces on Users Mental Models

Shortening speech prompts reduce attention allocation display; but might on the other hand deteriorate the users’ mental model. Thus the paper investigates effects of reducing time effort of speech via a transfer task, retrieval tasks and navigation-orientation tasks for three different strategies: (1) using earcons for menu orientation, (2) using commando based speech for interaction options, and (3) using uptempo speech for content based information. Results show that earcons are well qualified to not impair navigation-orientation performance. Commando based speech leads to even better retrieval performance than sentence based representation of interaction. Solely uptempo speech decreased retrieval performance.