Heart rate and respiratory rhythm of telegraph operators, card punchers and operators of the automatic mail parcel sorter were investigated in order to assess their mental work load. Heart rate and respiration ravealed the steady state patterns after the period of initial fluctuation. The increase of heart or respiratory rate during the steady state was not so remarkable. As the working period was prolonged, the alternations of temporary tachy- and bradycardia, accompanied with inhibited arhythmic respiration, was often observed for a few minutes at the beginning of pauses or during the rest period after work. The steady state was soon restored as the work was resumed again. In that case, a paradoxycal decrease of heart rate during work was often observed. The described disturbances of heart or respiration rate may be presumably due to the temporary functional unbalance of the sympathetic and parasympathetic nervous systems which were released from the cerebral control as the subject took rest.If the working period was experimentally much prolonged, a disturbed pattern of heart or respiration rate with tachycardia was usually demonstrated, which, however, was not the case in hte actual business work. The author is of the opinion that the investigation on the disturbances of vegertative functions may contribute to the physiological assessment of the work load and to the improvement of working conditions.

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The main factor that affects the heart rate of the modern aircraft pilots during the actual flight is considered to be a mental stress rather than a physical one with particular exception of the G stress. Electrocardiograms of the pilots, which were recorded during various patterns of the actual flight in a light aircraft (T-34, F-86 F, and F-104 J), were investigated and the relationships between chages of the heart rate and stresses, especially mental strain or G stress, were discussed. The results are summarized as follows. 1. Pulse rate showed a considerable increase during the actual flight corresponding with each flight pattern such as taking-off, level flight, or landing, in which the effects of G force were believed to be negligible. For example, during the level flight, in which the pilots were most relaxed, pulse rate was maintained at about 50% level above the normal resting value on the ground. Pulse rate during the taking-off landing showed an increase by about 80%. In super-sonic jet fighter, the pilots with pressure suits showed a much more increase in their heart rate during ordinary flight. These facts may indicate that pilots are in a considerably strained mental condition during the fight. 2. Pulse rate of pilots and G value during acrobatic flights such as loop, immelman turn, airlon roll, barrel roll, spin, and clover leaf were studied by T-34 trainer. Maximum Gz during these acrobatic maneuvers in this type of aircraft was about +3Gz, and the pulse rate of pilots showed a nearly positive correlation with +Gz. Increasing rate of pulses by the acrobatic G stress was about 10 to 15 beats per minute per +1Gz, while in the human centrifuge experiments it was about 8 beats per mintue per +1Gz. This difference between actual flight and human centrifuge experiment may be considered to be due to an additional mental strain in the actual flight.

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心拍数によって精神作業の負荷強度を評価するための実験的うらづけを得るため,知的作業(数列の逆唱)の難易度(数列の桁数)を変化させ,これによって作業中の心拍数がどのような影響をうけるかを,36人の男女被験者について観測した。その結果,作業の困難度増すと心拍数の増加傾向も著大となり,心拍数が精神負担度の指標としてきわめて有効なことを確認した。

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動力車運転士などが,列車運行に支障をきたしたり,人身事故をおこすような緊急事態にであったときの,心拍数・手掌皮膚抵抗値などの変動には,一定のパターンがみとめられた。電気機関車機関士が自殺者をれき過した場合,東海道新幹線電車運転士がトンネル内で,線路上の白布を土砂くずれとおもい非常停車した場合,犬の衝突ショックを人身事故と考えて非常停車した事例,および,東海道新幹線列車集中制御室司令員が人身事故の報告をうけた場合の4事例では,いずれも,心拍数が60∼80から上昇して40∼60秒で120∼140のピークに達し,そののち1∼2分で80∼90に復帰し,のち数十分そのレベルがつづくという一定のパターンがみとめられた。手掌皮膚抵抗値は,精神電気反射の頻発とともに大きく低下し,再びもとにもどるが,数十分間は復帰傾向をみない場合もあった。他方,東海道新幹線電車運転士が早避おくれの作業者を発見し,あやうく触車をまぬがれた一例では,心拍数は一過性に急上昇したが,後影響はみられなかった。 こうした生理的反応のパターンは,緊急事態にともなう情動性の反応と解され,そうした反応のおこり方と,背景にある作業性神経緊張や緊急事態後の行動錯誤との関連について考察した。

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mental stressがTAFテストにより客観的にとらえられるかどうかを,心的要素の強いとみとめらえる各種作業について実証的検討を行ない,TAFテストが作業の質的差異を合理的によく表現するものとみとめられた。ついでTAFがいかなる生理機能に対応するものであるかという本質的な機序を解明する目的で,TAFと自律神経平衡および脳波α波との関連について,騒音暴露,筋運動負荷,皮質麻酔剤投与等による実験研究をおこなった。 これらの結果からmental stressの評価において,TAFの変動は量的なものを表現し,自律神経平衡(CPT-動揺値)はその質的なものの表現に役だつという考えに到達した。

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精神作業負担は負担-反応系の様相によって把握せざるをえない。いま,質量ともに同一の負担をかけても,各人に同一vectorの反応はえられない。各人異なったHost-conditionをもっているからである。もちろん,各人の感受性の差によって,反応程度も異なる。 各人の異なったHost-conditionを持つ負担-反応系の様相を解釈するためには,つぎのごとき点を理解することが必要である。すなわち, 1) 神経負担に対する潜在的な受容性, 2) 反応の異なったvectorをふくめた偏差,である。

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Telegraph and telephone services compel the operators to work by imposing on them visual and auditory senses, manual cooperative actions, and nervous tension for quick and accurate reply. Accordingly, the fatigue of the operators caused by mental and sensory tension is likely to be angmented with the mechanization of equipment, the increase of the intensity of operation, and the midnight shift. Researches were carried out to make these points clear with the following approaches: (A)comparison of fatigue complaints among operators on various jobs and shifts in different offices of different scales; (B) measurement of flicker values related with working conditions of the operators; (C) recording physiological responses while working, such as heart rate, respiration, and galvanic skin resistance (GSR). Results are as follows: 1) a) Fatigue complaints of punchers and deliverers were most frequent as characteristic symptoms compared with those of other workers. In such jobs a tendency of accumulation and fixation of fatigue was seen. Communication and telephone operators came to the next. Those fatigue symptoms were mainly of neurosensory origin, such as strain of the eye and heavy-feeling of the head. Complaints of punchers were focussed on shoulder and waist due presumably to constrained working posture. b) Fatigue complaints were most frequently expressed by night-shift workers and less frequent in different kinds of workers in the order: evening shift workers, daytime workers for 8 hours, those of 6 hours, and half-day workers. At larger offices in the municipal area fatigue complaints of the operators were more pronounced than those at the smaller offices in the rural area. 2) Results of the flicker test on the operators also revealed some differences among jobs and shifts. A remarkable decrease of the flicker value was found in the night-shift workers, especially in female operators after a nap. 3) Physiological responses of the operators during the working time were manifold according to the job. a) Physical movements and acts necessary for operating work, such as reply to telephone calls and arrangement of slips in the telephone operators, stamping and typewriting in the printed form of communication operators, precision work and going up and down the stairs in the machinists, could easily provoke excited reactions in the heart rate, in the respiratory pattern, and in the galvanic skin resistance, as sensory and emotional stimuli. b) Generally speaking, a prompt elevation of nervous tension was observed from the beginning of work with a stationary condition after 20-40 minutes. After the pause of work, a temporary 'rest effect' was noted. However, after 5-6 hours from the beginning of the work or 1 hour after one set of continued operation, a definite increase of the heart rate (10-20% on an average) with greater fluctuations was noted. This was particularly remarkable at night work. c) In unskilled operators the 'rest effect' was scarcely noted, and the auto-correlation coefficient of heart rate revealed a marked difference compared with that in the skilled. This may be due to the greater nervous tension in the unskilled operators. It is concluded that the feature of fatigue caused by telegraph and telephone operations accompanied with neuro-sensory tension is influenced by various working conditions, especially hours of work, arrangement of pause, night-shift, frequencey of operations, constrained posture, and skillfulness of workers. Therefore, the necessity of improvement of these working conditions should be stressed.

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