One purpose of integrating voice interfaces into embedded vehicle systems is to reduce drivers’ visual and manual distractions with ‘infotainment’ technologies. However, there is scant research on actual benefits in production vehicles or how different interface designs affect attentional demands. Driving performance, visual engagement, and indices of workload (heart rate, skin conductance, subjective ratings) were assessed in 80 drivers randomly assigned to drive a 2013 Chevrolet Equinox or Volvo XC60. The Chevrolet MyLink system allowed completing tasks with one voice command, while the Volvo Sensus required multiple commands to navigate the menu structure. When calling a phone contact, both voice systems reduced visual demand relative to the visual–manual interfaces, with reductions for drivers in the Equinox being greater. The Equinox ‘one-shot’ voice command showed advantages during contact calling but had significantly higher error rates than Sensus during destination address entry. For both secondary tasks, neither voice interface entirely eliminated visual demand. Practitioner Summary: The findings reinforce the observation that most, if not all, automotive auditory–vocal interfaces are multi-modal interfaces in which the full range of potential demands (auditory, vocal, visual, manipulative, cognitive, tactile, etc.) need to be considered in developing optimal implementations and evaluating drivers’ interaction with the systems.Social Media: In-vehicle voice-interfaces can reduce visual demand but do not eliminate it and all types of demand need to be taken into account in a comprehensive evaluation.

Assessing SOD and associated WM resources have implications for targeted training for navigation in VEs and for the design of in-vehicle navigation systems.

Several studies have documented that the failure of drivers to attend to the forward roadway for a period lasting longer than 2-3 seconds is a major cause of highway crashes. Moreover, several studies have demonstrated that novice drivers are more likely to glance away from the roadway than experienced drivers for extended periods when attempting to do a task inside the vehicle. The present study examines the efficacy of a PC-based training program (FOCAL) designed to teach novice drivers not to glance away for these extended periods of time. A FOCAL-trained group was compared to a placebo-trained group in an on-road test, and the FOCAL-trained group made significantly fewer glances away from the roadway that were more than 2 seconds than the placebo-trained group. Other measures indicated an advantage for the FOCAL-trained group as well.

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Objectives: Information about drivers' experiences with driver assistance technologies in real driving conditions is sparse. This study characterized driver interactions with forward collision warning, adaptive cruise control, active lane keeping, side-view assist, and lane departure warning systems following real-world use. Methods: Fifty-four Insurance Institute for Highway Safety employees participated and drove a 2016 Toyota Prius, 2016 Honda Civic, 2017 Audi Q7, or 2016 Infiniti QX60 for up to several weeks. Participants reported mileage and warnings from the technologies in an online daily-use survey. Participants reported their level of agreement with five statements regarding trust in an online post-use survey. Responses were averaged to create a composite measure of trust ranging from −2 (strongly disagree) to +2 (strongly agree) for each technology. Mixed-effect regression models were constructed to compare trust among technologies and separately among the study vehicles. Participants' free-response answers about what they liked least about each system were coded and examined. Results: Participants reported driving 33,584 miles during 4 months of data collection. At least one forward collision warning was reported in 26% of the 354 daily reports. The proportion of daily reports indicating a forward collision warning was much larger for the Honda (70%) than for the Audi (18%), Infiniti (15%), and Toyota (10%).Trust was highest for side-view assist (0.98) and lowest for active lane keeping (0.20). Trust in side-view assist was significantly higher than trust in active lane keeping and lane departure warning (0.53). Trust in active lane keeping was significantly lower than trust in adaptive cruise control (0.67) and forward collision warning (0.71). Trust in adaptive cruise control was higher for the Audi (0.72) and Toyota (0.75) compared with the Honda (0.30), and significantly higher for the Infiniti (0.93). Trust in Infiniti's side-view assist (0.58) was significantly lower than trust in Audi (1.17) and Honda (1.23) systems. Coding of answers to free-response questions showed that more than 80% of complaints about Honda's adaptive cruise control were about the way it functioned and/or performed. Infiniti's side-view assist was the only one with complaints mentioning circumstances where it was used. Trust in forward collision warning, lane departure warning, and active lane keeping was not significantly different among vehicles. Conclusions: Driver trust varied among driver assistance technologies, and trust in adaptive cruise control and side-view assist differed among vehicles. Trust may affect real-world use of driver assistance technologies and limit the opportunity for the systems to provide their intended benefits.

There is limited research on trade-offs in demand between manual and voice interfaces of embedded and portable technologies. Mehler et al. identified differences in driving performance, visual engagement and workload between two contrasting embedded vehicle system designs (Chevrolet MyLink and Volvo Sensus). The current study extends this work by comparing these embedded systems with a smartphone (Samsung Galaxy S4). None of the voice interfaces eliminated visual demand. Relative to placing calls manually, both embedded voice interfaces resulted in less eyes-off-road time than the smartphone. Errors were most frequent when calling contacts using the smartphone. The smartphone and MyLink allowed addresses to be entered using compound voice commands resulting in shorter eyes-off-road time compared with the menu-based Sensus but with many more errors. Driving performance and physiological measures indicated increased demand when performing secondary tasks relative to ‘just driving’, but were not significantly different between the smartphone and embedded systems. Practitioner Summary: The findings show that embedded system and portable device voice interfaces place fewer visual demands on the driver than manual interfaces, but they also underscore how differences in system designs can significantly affect not only the demands placed on drivers, but also the successful completion of tasks.

Driver distraction inside and outside the vehicle is increasingly a problem, especially for younger drivers. In many cases the distraction is associated with long glances away from the forward roadway. Such glances have been shown to be highly predictive of crashes. Ideally, one would like to develop and evaluate a training program which reduced these long glances. Thus, an experiment was conducted in a driving simulator to test the efficacy of a training program, FOCAL, that was developed to teach novice drivers to limit the duration of glances that are inside the vehicle while performing an in-vehicle task, such as looking for a CD or finding the 4-way flashers. The test in the simulator showed that the FOCAL trained group performed significantly better than the placebo trained group on several measures, notably on the percentage of within-vehicle glances that were greater than 2, 2.5, and 3 s. However, the training did not generalize to glances away from the roadway (e.g., when drivers were asked to attend to a sign adjacent to the roadway, both trained and untrained novice drivers were equally likely to make especially long glances at the sign).

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