A Measurement Method for Visual Fatigue Through Clarification of Its Effects on the Human Body and Related Factors in VDT Operations.

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This research clarified a mechanism of human visual information processing as based on the processing of VDT operation, before examining visual fatigue. Human visual information processing was divided into three subprocesses. The recognition process from an internal representation stage of visual information to a recognition stage was modeled.Concerning the effects of VDT operation on human body, the effects on human visual system and central nervous system were focused on. Two experiments were carried out to examine these effects, compared VDT operation with hardcopy task. As the result, there were much more effects of VDT operation than those of hardcopy task, not only to the visual system, but also to central nervous system. The effects of work pace were also examined with visual fatigue and work performance as characteristics. It was obtained as the result that the self-paced work is much better for cognitive tasks than the machine-paced work.In order to clarify the effect of work contents, the relationship between two factors characterized work contants and visual fatigue.With considered the above results, a measurement method for visual fatigue was proposed in the present research. The method is to measure the decrease of channel capacity of central nervous system. The proposed method were applied to various tasks and work environments. As the results, the method was found to be able to detect the degrees of fatigue among various work environments.