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19 décembre 2002
Journal of Human Ergology 1973; 2; 75-89 
Temporal change of subsidiary behavior in monotonous work
 Kishida K
Institute for Science of Labour, Takatsu-ku, Sugao, Kawasaki, Japan  


Monotonous situations have become increasingly prevalent in industrial assembly line production systems where repetition of simple tasks tends to result in boredom and decrement of performance. The so-called 'gear wheel sentiment' of assembly workers seerns to have become stronger in recent years.

Relating the observations of workers' behavior and workers' subjective statements to the variability of the output, Wyatt et al. (1929) reported that monotonous repetitive operations greatly changed behavior patterns resulting in workers looking around, talking with neighbors, stretching,and yawning. Kirihara (l 960) further showed through introspective methods that boredom was extensively modified by the paced or unpaced nature of a repetitive task. Boredom is also known to be related to changes in physiological conditions of workers in terms of visual functions, electroencephalographic changes, and other indices of the level of arousal. It is thus postulated that the incidence of boredom varies widely in relation to the complexity of the task, and that the brief distractive activities intermediating the work are significant to maintain performance).

Recently Saito et al. have conducted studies in cooperation with a specialist committee on monotony problems sponsored by the Ministry of Labour. Their studies showed that the feeling of monotony accompanied by various changes in workers' attitude is greatly dependent upon the time reserve of the repetitive task. The author took part in these studies and has tried to reveal the relationship between the boredom and the subsidiary behaviorofworkers not directly relevant to the work. The presentpaperattempts to clarify the occurrence of such distractive behavior as a function of the time reser~e included in workin patterns. [...]

DISCUSSION : Increases in frequency of both chattering and other subsidiary activities such as changing positions, looking around, yawning, etc., were observed at all types of the work patterns including the severely paced conveyor work. Those behavioral changes had large individual differences and very high frequencies were usually found among 10-30 %. of the whole cases.

In the present study, the workshops showing the least increase in those subsidiary activities with the work were severely paced conveyor lines with fixed work rates. The workers on these paced lines had to work the same procedure through the day's shift at a constant and relatively fast rate. This might be against the expectation that a paced work would lead to more frequent compensatory movements due to its monotonous situations. In reality, however, these workers had less occasions to wait for the next assembly task, and the less chances they have to wait, the less was the subsidiary activities except chattering, as shown by Fig. 6 for one of these workshops. The limitation of voluntary subsidiary actions irrelevant to the assernbly work on these conveyor lines may be suggested by the fact that this kind of work produced very small variation of work cycles during the shift period. It is thus postulated that a strictly paced rhythm of conveyor work restrict the free onset of compensatory movements.

The conveyor lines with variable tasks showed in general earlier and higher increase of both chattering and other subsidiary actions, while the table system workers showed their moderate increase. Less frequent appearance of subsidiary behaviors in the table-type assembly work may be explained by the frequent changes of minor processes included in each relatively long cycle time. The marked increase of the cycle time in the later hours of the table system work indicates that the comparatively small frequency of the subsidiary behaviors was not due to the time restrictions. Frequent changes of working positions and motions as weil as frequent shift of attention would account for the reduction of the need for subsidiary activities. In contrast, the conveyor work, if moderately paced, brings about frequent compensatory activities in terms of chattering, changing positions, looking around, arranging hair, closing eyes, yawning, etc.

The incidence rate of these subsidiary behaviors was reduced by insertion of short pauses, lunch recess, or short gymnastics, especially among workers of the conveyor workshops with variable tasks such as bottling of various kinds of enamel manicures. Such workers also revealed a decrease of subsidiary actions during the last half-hour period of the working day. These facts suggest that the increase in subsidiary activities is produced by the monotonous working situations.

Although chattering with neighbors can be done without influencing manual operations, it was less frequent on conveyor lines with severe pacing. Since no correlation was found between waiting frequency and chattering even in a severely paced workshop, the observed suppression of chattering on such conveyor lines may be due to the fast pacing situation as a whole. On the conveyor lines with variable tasks where the chattering was the most frequent, its frequency was correlated with frequency of other subsidiary activities.

Wyatt et al. (1934) and Kano (1962) pointed out that chattering of workers increased in accordance with the reduction in work output. WYATT suggested that it reduced the boredom and drowsiness. In the workshops of the present study where the pace of work was strictly controlled by the conveyor speed, however, not only chattering but also other voluntary subsidiary actions were too reduced to compensate the boredom. These workshops had more persons whose critical flicker frequency or color-naming speed much declined. The workers under such strict pacing by the conveyor belt also had higher rates of subjective fatigue feelings than assembly workers of other working patterns. The fatigue feelings were dominant especially for symptoms of the dull-drowsy factor and for shoulder stiffness.

Saito et al. have shown that the reduction in the detection rate of wrong boules was closely associated with the rate of drowsiness during boule inspection. The high rate of drowsiness was usually observed in workshops of inspection or assembly tasks where the strictly paced work rate did not allow changes in the working habits. In one of serial reports on industrial monotonous work, Saito et al. (1969) discussed the relationship between distractive actions including chattering and what they called negative work feelings. They concluded that the increased distractive activities of monotony workers might be dependent upon the appearance of feelings of boredom and aversion. The author has confirmed that the critical flicker frequency was maintained at a high level when chattering was vivid and frequent and hence the negative feelings of workers were little.

Although it is clear that momentary distractions by periodical changes of activity, brief rest pauses, chattering, and others serve to maintain performance, such distractive behavior seemed to be remarkably reduced in paced work when the workers are apt to be drowsy, their compensatory effects being all the more decreased. In the same manner, the work patterns allowing less free activities of individuals result in lower level of arousal and in decrement of performance. It is reasonably assumed that the boring effects of repetitive work on strictly paced conveyor lines may be accelerated by the restriction of subsidiary behaviors. Thus the frequency of subsidiary activities may be used as an indication of the degree of freedom of paced work. Ample reserve time for those distractive activities should be considered important to prevent the monotony effects of repetitive work patterns.