Studies on Multiple Approaches to Workload Assessment

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1. Workload Assessment in Line Workers by NASA-TLX : The NASA-TLX was revised for line workers. Four surveys were performed in an air-conditioner company. The results show significant correlation between WWL and AWWL.The test-retest correlation was also significant. Subscale scores could detect the differences in characteristics of the lines. However, these scales may not have sensitivities to a postural load. Further revisions have to be done.2. Mental Workload Assessment by Psychophysiological Indices : ECG (HRV,TWA), fingertip plethysmogram, perspiration, respiration and pupil area were recorded from sixteen male subjects. Wood piece puzzle to make a geometric pattrn (PZ), two-dimensional compensatory tracking task (FL) and numeric logical task (MN) were designed as mental tasks. The task duration for PZ was eight minutes. Three levels of difficulty were set in FL and MN task and four minutes were allowed to perform each task. New pupil measuring system was designed and developed. However, subject's eyelid disturbed the pupil measurement. It must be improved. Subjective workload was measured by NASA-TLX and Type A scores and state anxiety scores were obtained. The results show that HRV parameters were much affected by irregular respiration patterns nevertheless the subjects were instructed to control their breathing. On the other hand, amount of sweat correlated with task difficulty slightly. Furthermore, task specific responses were observed which suggest that the physiological responses differ between different kind of tasks even if the subjective workload is the same level.