|Sven Reichel, Jasmin Sohn, Ute Ehrlich, André Berton and Michael Weber|
Mobile Internet access via smartphones puts demands on in-car infotainment systems, as more and more drivers like to access the Internet while driving. Spoken dialog systems (SDS) distract drivers less than visual/haptic-based dialog systems. However, in conversational SDSs drivers might speak utterances which are not in the domain of the SDS and thus cannot be understood. In a Wizard of Oz study, we evaluate the effects of out-of-domain utterances on cognitive load, driving performance, and usability. The results show that an SDS which reacts as expected by the driver, is a good approach to control incar infotainment systems, whereas unexpected SDS reactions might cause severe accidents. We evaluate how a dialog initiative switch, which guides the user and enables him to reach his task goal, performs.