Self-report scales alone cannot capture mental workload (original) (raw)
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The Psychometrics of Mental Workload: Multiple Measures Are Sensitive but Divergent
Objective: A study was run to test the sensitivity of multiple workload indices to the differing cognitive demands of four military monitoring task scenarios and to investigate relationships between indices. Background: Various psychophysiological indices of mental workload exhibit sensitivity to task factors. However, the psychometric properties of multiple indices, including the extent to which they intercorrelate, have not been adequately investigated. Method: One hundred fifty participants performed in four task scenarios based on a simulation of unmanned ground vehicle operation. Scenarios required threat detection and/or change detection. Both single- and dual-task scenarios were used. Workload metrics for each scenario were derived from the electroencephalogram (EEG), electrocardiogram, transcranial Doppler sonography, functional near infrared, and eye tracking. Subjective workload was also assessed. Results: Several metrics showed sensitivity to the differing demands of the four scenarios. Eye fixation duration and the Task Load Index metric derived from EEG were diagnostic of single-versus dual-task performance. Several other metrics differentiated the two single tasks but were less effective in differentiating single- from dual-task performance. Psychometric analyses confirmed the reliability of individual metrics but failed to identify any general workload factor. An analysis of difference scores between low- and high-workload conditions suggested an effort factor defined by heart rate variability and frontal cortex oxygenation. Conclusions: General workload is not well defined psychometrically, although various individual metrics may satisfy conventional criteria for workload assessment. Application: Practitioners should exercise caution in using multiple metrics that may not correspond well, especially at the level of the individual operator.
Towards the Shape of Mental Workload
PsycEXTRA Dataset
Mental workload is a measure of how much mental effort a person devotes to one or more tasks. In two experiments, we investigated the effect of multiple identical tasks on human performance in terms of both accuracy and response time for a visuo-spatial task set and an auditory task set. The findings showed that participants performed linearly worse on some measures of performance when the number of tasks increased, while other measures showed two distinctive variations on this linear decrease in performance. We discuss these results in terms of their effect on the traditional linear representation of workload in IMPRINT (IMproved Performance Research INtegration Tool, Archer & Adkins, 1999), a task-based human performance modeling system.
A Multiple Processing Resource Explanation of the Subjective Dimensions of Operator Workload
1984
SSCUPtY-CLASSIFICA ION OF TInS PASS Mh= Do& E&ae similarity. Scaling and clustering analyses of the similarity data produced subjective dimensions/clusters of workload that were explained in terms of resource demand, task structure, and task characteristics. Data collected to support this analysis-task performance, physiological measures of heart period variability, effort ratingsrevealed three primary dissociations. These dissociations were explained by using the parameters of Wickens' multiple resource theory: 1) When contrasting subjective ratings with performance, the former was relatively more sensitive to the number of tasks performed concurrently, while the latter was relatively more sensitive to the difficulty of a single task, particularly if this difficulty was related to responding. 2) Subjective difficulty ratings did not discriminate a task performed concurrently with an identical task from a task time-shared with a different task. However, performance was reliably better in the second configuration. 3) While as noted in (2), time-sharing two differenttasks, using separate resources lead to better performance, this condition also yielded higher cardiac measures of mental workload.
Psychophysiological Metrics for Workload are Demand-Sensitive but Multifactorial
Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2014
Various psychophysiological indices of mental workload exhibit sensitivity to task demand factors, but the psychometrics of indices has been neglected. In particular, the extent to which different metrics converge on a common latent factor is unclear. In the present study, 150 participants performed in four task scenarios based on a simulation of unmanned vehicle operation. Scenarios required threat detection and/or change detection. Both single-and dual-task scenarios were used. Workload metrics were derived from the electroencephalogram (EEG), electrocardiogram (ECG), transcranial Doppler sonography (TCD), functional Near Infra-Red (fNIR) and eyetracking. Subjective workload was also assessed. Several metrics were appropriately sensitive to the differing levels of task load presented by the four scenarios. However, factor analysis identified multiple factors, each of which was associated with a single response system only, with no general factor. Caution should be used in assessing workload in the individual operator.
Applied Psychology-an International Review-psychologie Appliquee-revue Internationale, 2004
and simultaneously (dual task). The results of the ANOVAs performed showed that there are no differences with regard to the three instruments' intrusiveness, and that among the three subjective workload instruments WP has an outstanding sensitivity to the different task manipulations. To evaluate the diagnosticity of each of the three instruments canonical discriminant analysis was used, and this demonstrated that the three multidimensional ratings provided diagnostic information on the nature of tasks demands that was consistent with the a priori task characterisation. However, the diagnostic power of WP was clearly superior to that obtained using TLX or SWAT. Pearson correlations between each performance and each subjective workload measure were calculated to evaluate the concurrent validity of each instrument with task performance, and to assess the convergent validity of the instruments. The three coefficients were positive and near to one, showing the high convergent validity of the three instruments considered in this research. Implementation requirements and subject acceptability were also compared. Finally, practical implications on the three assessment approaches are mentioned.