The effect of repeated vigilance tasks on respiratory rate, heart rate, galvanic skin reflex (
GSR), signal detection and subjective feelings were studied in three sub-jects. The subjects performed a simple task employing a rate of 35 signals/hr during 2-hr once a day and repeated it throughout a 9-day period.
The mean values of respiratory rate and heart rate during the 2-hr period of the task maintained the same level throughout the 9-day period. However, the mean value of GSR frequency showed a higher value on the third day as compared with on the other days and signal detection accompanied by GSR during the 2-hr period of the task indicated a higher value on the second or third day. On and after the fourth day these values tended to decrease with fluctuations.
The mean values of signal detection during the 2-hr period of the task tended to show approximately the same level throughout the 9-day period except for the decre-ment of that on the fifth day in one subject and on the seventh day in another sub-ject.
Subjective intention to perform the task had a tendency to decline toward a lower level in the period of 5-8 days.
On the relation between these parameters and signal detection obtained from the three subjects, it was found that variances of heart rate,
GSR frequency and signal detection accompanied by
GSR during the 2-hr period of the task correlated with the mean values of signal detection during the same period of the task. Correlation coef-ficients between
GSR frequency and time course, and between signal detection accompa-nied by
GSR and time course during the task correlated with the mean values of signal detection. On the correlations for each subject, in one of the three subjects variances of heart rate and correlation coefficients between signal detection accompanied by
GSR and time course correlated with signal detection, and in another subject there was a correlation between variances of GSR frequency and signal detection.
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