Measuring the Workload of Sustained Attention: Further Evaluation of the Multiple Reources Questionnaire

This study confirms and extends a recent finding by Finomore et al. (2006) that the Multiple Resources Questionnaire (MRQ; Boles & Adair, 2001) can be of effective value in assessing perceived mental workload in vigilance tasks. As in the earlier study, the MRQ was evaluated by comparing it against a standard measure of workload in vigilance research, the NASA-Task Load Index (NASA-TLX; Hart & Staveland, 1988), in its sensitivity to experimental factors known to influence task demand. The factors in this case were the sensory modality of signals and event rate. Both workload scales showed that the level of workload was substantial, and that workload was greater for the fast than slow event rate. The NASA-TLX indicated that workload was greater when monitoring visual than auditory stimuli. With the MRQ, the sensory modality of signals emerged as a moderator variable for event rate; the effects of event rate were restricted to visual signals. The MRQ also identified resource dimensions that were utilized in the vigilance tasks that are not included in the NASA-TLX. Thus, the MRQ exhibited the properties of sensitivity and diagnosticity characteristic of a valid workload scale (O'Donnell & Eggemeier, 1986).