Abstract
In the fatigue investigation decrement in CFF values have been reported to have a causal relationship with physical and mental fatigue and change in the consciousness level of the cerebral center. However, nowadays some investigators have raised suggestion that the decrement in CFF values would reflect a reduction of functions of such regions as the retina and the optic nerve located the peripheral optic chiasm. To examine this question, 8 subjects are tested under the four experimental conditions; three of loading methods of the first rank adding (Kraepelin) work method on CRT, paper, and voice, and the no work method. Under each condition, CFF is measured (by modifying correction method) for 100 minute at intervals of 10minutes. The results of the CFF value decrement are-10.4%/10th time on CRT, -7.0%/9th time on paper, -12.4%/10th time by voice, and -3.1%/11th time for no work. It is supposed that Kraepelin work with voice shows the result from intersively used memory center, compared to the works on the CRT and on the paper. In addition, the load during no work seems to be a reduction of the conscious level of the cerebrum caused by feelings of restriction and tedium. From these results and from the viewpoint of simplicity of measurement as well as judging accuracy, the decrement in CFF values is regarded to be effective as a judging index not for peripheral fatigue of the optical system but also for central fatigue.
