Effects of Workload and Task Complexity
on Driving and Task Performance
for In-Vehicle Displays As Assessed by Visual Occlusion

Tsimhoni, O., Yoo, H., and Green, P.

December, 1999

Given the recent proliferation of in-vehicle systems, understanding how drivers deal with the visual demands of driving while operating these systems is essential. To provide such, 16 subjects drove a simulator on roads with long curves of several different radii while providing verbal responses to questions about the content of electronic maps displayed on the center console. In additional sessions, visual demand of the same road segments was measured using the voluntary occlusion technique.

Task completion time while driving was correlated with static completion time, generally increasing when the task was performed while driving. It decreased, however, for short tasks, especially when only one glance was made. As driving workload increased, subjects made shorter glances at the display, made more of them, but waited longer between glances. The net effect was a slight decrease in total glance duration (eyes-off-the-road time). As driving workload increased, driving performance became worse.

These results suggest a complex interaction in which drivers attempt to compensate for increased visual demand or task complexity, which leads to a statistically and practically significant decline in driving performance with task duration and driving workload.

Graphical Abstract (.pdf) | UMTRI-99-37 Full Report (.pdf)


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