The development of a duration method for measurement of visual fatigue

Abstract

Many workers claim to feel the visual fatigue caused by vigilance tasks. V erbal reports of the visual fatigue have not corresponded to results by ophthalmological and psychophysical testings. Our previous studies showed that temporal sensitivity in vision changed concomitant to the visual fatigue, and that the change of the sensitivity appeared in difference in dynamic range of responses obtained from threshold measurement and did not in the thresholds themselves. Based on the studies, a new fatigue testing method called as the duration method was developed and an apparatus for measuring the temporal sensitivity to the light was devised. In results of Exps. 1 and 2, an available condition for measurement of visual fatigue was found. In Exp. 3, under the available condition, effects of the three local lighting conditions were shown quantitatively in differences in the dynamic range. In this experiment three subjects performed writing-tasks in everyeight hours in each of the three conditions. Interday variations were counter balanced.