The objectives of this research were: (1) to compare the distraction potential of voice-based versus visual/manual interfaces for selected transactions undertaken while driving, (2) to examine the effect of performing tasks of differing complexity on driving performance, and (3) to evaluate the potential of using eye-tracking technology to make inferences about changes in subjects’ allocation of attention while performing specified in-vehicle tasks while driving. Twenty-one subjects completed two sets of eight laps around a 7.5-mile test track during two four-hour sessions. They drove an instrumented vehicle while performing a combination of car following, peripheral target detection, and secondary (in-vehicle) tasks of varying complexity. Subjects performed one set of laps with each of two interfaces, voice-based and visual/manual. Secondary tasks comprised three categories including baseline tasks (radio tuning, phone dialing), simple tasks (message retrieval plus voice memo creation), and complex tasks (simple task components plus phone dialing and information retrieval from automated phone systems). Measures of driving performance, target detection, secondary task performance and eye movements were recorded. Analyses were conducted to determine whether the voice-based interface reduced the relative distraction potential for secondary tasks of varying complexity. Performing secondary tasks while driving resulted in significant decrements to vehicle control, target detection and car-following performance. The voice-based interface helped reduce the distracting effects of secondary tas k performance. Improvements were relatively minor and limited to vehicle control and visual performance measures. There was no effect on car-following measures, suggesting the voice interface had little effect on cognitive distraction. The results suggest that voice interfaces may not provide enough help to overcome the cognitive distraction associated with secondary tasks of increasing complexity, particularly in driving situations that require time-space judgments and tactical decision-making. (Author/publisher)
Samenvatting