In Vehicle Voice Control Interface Evaluation: Preliminary Driver Workload and Risk Analysis

This project evaluated distraction and relative risk associated with using voice control systems (VCS) while driving. The objective was to explore potential empirical measures and to use a modeling approach for evaluating risk with these voice-based systems. The project included three studies. Study 1 and Study 2 were designed to assess potential measures of the workload and demands on the driver imposed by voice-based and hybrid (audio plus visual) tasks. Participants interacted with a “Wizard of Oz” VCS while driving and a novel radio tuning benchmark task was used. Study 1 (n= 9) compared response times for the tactile detection response task (TDRT), which is a standardized measure of cognitive load, with a modified remote detection response task (RDRT) which was implemented in this study to provide a complementary measure of visual attention toward the forward roadway. Response time was sensitive to differences between VCS tasks, and there was a significant interaction between detection response task (DRT) type and VCS task. Study 2 (n= 9) included both on-road data collection and data collection with a driving simulator. In three different sessions, measurement protocols included TDRT, response time to the lead vehicle (LV) brake light, speed matching to a speed-varying LV, and off-road eye glance measures. Results indicated that task completion time, TDRT performance, and eye glance measures distinguished between VCS tasks and provided similar results in the on-road and simulated driving contexts. Study 3 used an analytical approach to develop relative risk estimates and crash severity estimates for the VCS …