Abstract
A dual-task driving paradigm was used in this study to investigate (a) the effect of increased workload on the extent of spatial attention and (b) whether the measure of useful field of view (UFOV) predicts the decrement of performance in a light detection task with increased workload. A car-following task and a peripheral light detection task were used. In the car-following task, drivers tried to maintain a predetermined distance from a leading vehicle (LV) as it varied its speed. Two levels of workload were examined by manipulating the amplitude of the LV's speed variation. In the light detection task, drivers detected a light change in a light array located above the roadway. The horizontal position of the target was manipulated. The performance in the car-following task was assessed by using both global measures (distance headway, standard deviation of distance headway, and root-mean-square velocity error) and local measures (gain, phase, and coherence). The performance in the light detection task was measured by using accuracy and response time. The drivers' UFOV scores were also collected. Overall, it was found that (a) increasing the workload resulted in performance decrements in both the car-following task and the light detection task, (b) decreased performance in detecting light changes occurred farther away from the center of display, and (c) the UFOV scores significantly predicted the increase in the response time with a higher workload when the target was close to the center of display.