The objectives of this study were to compare the degradation in driving performance associated with secondary tasks performed with voice-based and visual/manual interfaces. These included such tasks as radio tuning, phone dialing, and more complex involving a sequence of interactions with an in-vehicle computer system. Twenty-one drivers (10 men, 11 women) participated in the experiment. They drove an instrumented vehicle while performing a combination of car-following, peripheral target detection, and secondary tasks on a closed test track. Drivers compensated for increased task demands associated with secondary tasks by increasing their following distance. Performing secondary tasks also resulted in significant decrements to vehicle control, target detection, and car-following performance. The voice-based interface was useful in reducing the distracting effects of secondary task performance. Modest improvements were observed for measures of vehicle control and target detection but not for car following. The results of this study demonstrated that performing in-vehicle tasks required diversion of both peripheral (visual and manual) and attentional (cognitive) resources from driving. The voice-based interface helped to reduce the peripheral impairment but not the attentional impairment.
Abstract