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- Title
The psychometrics of mental workload: multiple measures are sensitive but divergent.
- Authors
Matthews, Gerald; Reinerman-Jones, Lauren E; Barber, Daniel J; Abich 4th, Julian; Abich, Julian 4th
- Abstract
<bold>Objective: </bold>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.<bold>Background: </bold>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.<bold>Method: </bold>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.<bold>Results: </bold>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.<bold>Conclusions: </bold>General workload is not well defined psychometrically, although various individual metrics may satisfy conventional criteria for workload assessment.<bold>Application: </bold>Practitioners should exercise caution in using multiple metrics that may not correspond well, especially at the level of the individual operator.
- Publication
Human Factors, 2015, Vol 57, Issue 1, p125
- ISSN
0018-7208
- Publication type
journal article