Ocular Activity as a Measure of Mental and Visual Workload

Abstract

The mental workload construct is examined along with visual workload in order to discriminate the relationship between the converging constructs. Six ocular activity variables were measured in order to test convergent and discriminant properties with regards to visual and mental workload. Three pilot crews flew six flight scenarios in which subjective and physiological mental workload measures were analyzed across task difficulty and task differences (pilot on-controls versus pilot off-controls). Results indicate less subjective mental workload for the hover task compared to the action on contact task and greater ocular fixation duration variability for the lower difficulty task. Blink interval was greater for the pilot on-controls and saccadic extent was greater for the pilot off-controls. Data suggest that blink interval and saccadic extent are diagnostic of different aspects of visual workload, whereas fixation duration variability is sensitive to mental workload.