Abstract
OBJECT OF THIS STUDY: The object of this study is to make an exprimental observation of the rest-pauses on psychophysical functions of a workman in the course of making process of Brake-shoe-adjusting-rods by means of striking hammers at the governmental railway factory in Japan.
EXPERIMENT: The subject in this experiment was a healthy labourer (aged 34). Experiment was carried out in Sept.&Oct. 1933. The experiment were devised into five series. The ratio of rest-pauses to work hours in a whole day is as follows.
workinghours rest-paues
(1) 0: 200
(2) 100: 90
(3) 100: 80
(4) 100: 70
(5)100: 60
The method of expe iment is as follows.
(1) Hourly change in accomodation of the eye.
We have measured the range of accomodation of the right-eye with the accomodometer (devised by Dr. Ishihara, Prof. of ophthalmology, Tokyo Imperial University.)
(2) Hourly change of discrimination of two points on the skin of left cheek was tested by the aesthesiometer.
(3) Hourly variation of output.
The quality and quantity of Brake-shoe-adjusting-rods produced were hourly recorded.
(4) Observation of the variation in motion process of the workman.
(5) Introspection of the workman.
(6) Illumination, temperature, humidity and cooling power of air at the workp ace were also investigated.
RESULTS: Following results were obtained with a subject whose sleeping hours were between 7 and 8 hours.
(1) Fatigue in the accomodation of eyes has a tendency to grow the less in proportion to the length of rest-pause, though it is nearly the same when the rate of rest-pause is 70%......90%. But in case the rate is lowered to 60%, the fatigue is much greater than when it is over 70%.
(2) The more the hours of rest-pause are shortened, the more tends the two points limen of the skin to be enlarged, and also the more inaccurate grows the cutaneous perception in its judgement, though while the rate of restpause is 70%......80%, there can hardly be found any change. When the rest-pause is at the rate of 70%, the spacial limen in the afternoon more or less enlarged and in case the rate is lowered to 60%, it can be observed to grow much larger than in the former three cases.
(3) To investigate producing process from the standpoint of required hours, more hours are generally taken in the afternoon-work in accomplishing the same amount of work, when the rate of rest-pause is 60%-70% than when it is 80%-90%. The amount of products is greatest when the rate is 70%-80%, and the failures, too, are the least.
(4) As to the subjective consciousness of fatigue on the part of the operators, it is the least felt when the rate of rest-pause is 90%, and the case when the rate is 80%-70% cames next, and at the rate of 60% the workers generally complain of remarkable exhaustion. It was when the rate was 80% that they could keep on working with pleasure and contentment.
(5) Motions of operators, as a whole, are not so much smooth in case the rate of rest-pause is 90%, because, the hours of work being too short, motions can hardly attain their full development. But when the rate is 80%-70%, operators are smooth and quick in motion. Under the 60%, the form of the motion is corrupted, with much increase of irregular motions, and mental saturation and fatigue can quite notably be detected.
For the details of this experiment, see my japanese text.
