On the Visual Distraction Effects of Audio-Visual Route Guidance

Abstract

This is the first controlled quantitative analysis on the visual distraction effects of audiovisual route guidance in simulated, but ecologically realistic driving scenarios with dynamic maneuvers and self-controlled speed (N = 24). The audiovisual route guidance system under testing passed the set verification criteria, which was based on drivers' preferred occlusion distances on the test routes. There were no significant effects of an upcoming maneuver instruction location (up, down) on the in-car display on any metric or on the experienced workload. The drivers' median occlusion distances correlated significantly with median incar glance distances. There was no correlation between drivers' median occlusion distance and intolerance of uncertainty but significant inverse correlations between occlusion distances and age as well as driving experience were found. The findings suggest that the visual distraction effects of audiovisual route guidance are low and provide general support for the proposed testing method.

Visual Distraction Effects between In-Vehicle Tasks with a Smartphone and a Motorcycle Helmet-Mounted Head-Up Display

“…The distraction potential of these two devices were assessed with red and green in-vehicle glances as defined by Kujala and Mäkelä [17]. The verification threshold for green glances was set to 68 % (min) and for red glances maximum to 6 % (max) [14,15]. Overall, the Nuviz HUD tasks passed the set verification criterion for green glances, the percentage of green glances being 68.6.…”

“…For measuring the visual distraction potential of the in-vehicle tasks, we used a method by Kujala and Mäkelä [17]. The same method has been previously applied to study visual distraction potential of audio-visual route guidance [15] and different text entry methods [14]. This method utilizes visual occlusion technique, originally introduced by Senders, Kristofferson, Dietrich and Ward [28].…”

“…A green glance refers to an in-vehicle glance length that is at or below the baseline data's median occlusion distance for the route point and therefore can be considered as an appropriate glance. The verification threshold for green glances has in previous studies [14,15] been set to 68 % (min) of all the invehicle glances made during the task. To pass the verification criterion, the task should have 68 % or more of green glances.…”

“…At these occasions, the invehicle task has caught the driver's attention for longer time than what the majority of the 97 drivers would have preferred to drive without vision on that route point. The verification threshold for red glances has been set to 6 % (max) [14,15] of all the in-vehicle glances made during the task. If the task's red glances exceed 6 %, the task fails the verification criterion.…”

“…The verification threshold for green glances was set to 68 % (min) [14,15]. According to one-sample sign test, the Nuviz HUD task passed the verification criterion for green glances (see Figure 3), the percentage being 68.64 (p = .376).…”