The Time Cost of Head-Up Displays for Older Drivers: Critical Event Onset, Task Location, and Display Type

The principle advantage of a head-up display (HUD) is that a driver does not have to take their eyes off the road. However, the advantage afforded by a HUD may be lost when surprising or unexpected events occur in the traffic environment. This study sought to determine the time-costs for elderly drivers associated with responses to the appearance of a pedestrian (critical event) while engaged in a HUD task. Sixteen older drivers (65 to 81, Mean = 73) interacted with a number of tasks presented in a low-cost driving simulator. Critical event onset after engaging in a HUD task (+100, +250, +1000 ms), display location (head-up, head-down), tracking difficulty (easy, hard), and display type (visual search, verbal memory) were the within-subjects variables. Analyses of perception-response time (PRT) and missed events (error) indicate that braking to a critical event, while performing a display task, is affected by the interaction between the temporal and spatial limitations of visual attention. HUD design and safety issues are briefly considered.