Controlling for Individual Differences in a Dual-Task Setting: Equating the Baselines of Single Task Performance

Abstract

Individual differences in human performance is an issue that confounds many studies and has not been properly controlled in the ergonomics/human factors literature. This paper examines the concept of individual differences in performance primarily from the perspective of cognitive performance. A study was designed to test the effect of a secondary visual task on a primary visual task. In one condition, participants performed the dual task, while assigning no weight to the secondary task. In the second condition, the primary task was performed simultaneously with the secondary task. The effect of the added workload was measured via the effect on primary task performance. In the baseline portion of the task participants had their baseline (80–90% accuracy) of performance collected by adjusting the stimulus duration. The individual participant stimulus duration was then used as the experimental stimulus duration and the effect of secondary task performance on primary task performance was measured.