Effect of Sensory Modality on Performance, Workload, and Frontal Lobe Oxygenation in a Standard Vigilance Task

The purpose of this research was to compare vigilance performance over time for visual, auditory, and vibrotactile tasks, while simultaneously recording oxygenation in the frontal lobe to assess physiological resource utilization. Subjective workload was assessed in each condition using the NASA Task Load Index (NASA-TLX). The data indicate a significant effect of time-on-task in all experimental conditions, with the vigilance decrement asserting in each modality condition within the first twenty minutes of the task. Significant differences in overall hit rates and nonparametric sensitivity (A′) were found between the loosely coupled visual modality and the closely coupled tactile and auditory modalities. Conversely, frontal lobe oxygenation increased with time-on-task, possibly reflecting increased processing demands as cognitive resources wane. The results suggest that although the vigilance decrement exists for all modality conditions, tactile vigilance tasks may be performed as efficiently as auditory vigils, with no significant differences in workload or physiological resource utilization.