ABSTRACT
This study assesses the degree to which three demand levels of an auditory delayed digit recall task impact visual attention, pupil diameter and simulated driving performance. Changes in horizontal gaze dispersion and reduced lateral variation during the dual task periods indicate a more centralized allocation of visual attention during periods of heightened cognitive load. This pattern was consistent across the first and second presentations of each task. At the highest demand level, pupil diameter increased significantly over other dual task periods and single task driving. Pupil diameter was moderately impacted by task repetition, suggesting some habituation to the novelty of the task. The overall results indicate that pupil diameter was a more sensitive measure of changes in workload with repeated task exposure than visual attention and driving performance measures in the context of the simulation. In an on-road study with the same secondary task, gaze became significantly more centralized as the level of cognitive workload increased. Although this level of discrimination was not replicated here, taken together, the results further highlight the usefulness of gaze dispersion as an indicator of cognitive workload.
