The Effects of Various Conditions on Subjective States and Critical Flicker Frequency
Several studies are reported in which CFF was found to be related to subjective feelings of activation or fatigue.
After the intake of 5 mg Diazepam (Valium), eight male subjects showed a marked decrease in CFF and a significant shift of subjective reports of tiredness.
In a field study of 68 air traffic controllers, the CFF showed a significant correlation with subjective reports of fatigue and it decreased more for night-shift than for day-shift personnel.
In a laboratory experiment, 25 subjects were exposed once to a monotonous situation (counting nails for 3 hours), and once to an activating situation (psychomotor tests, music). The monotonous situation showed a decrease of 2 Hz in the CFF and a shift of selfrated subjective state toward decreased “motivation” and “ability for action.” In the activating situation, the CFF did not change, while the subjective state shifted toward greater motivation.
In another laboratory experiment, 18 subjects performed a repetitive task for 3½ hours, with three different degrees of mental load. The results showed a decrease of CFF in tasks with low and with high mental loads, while the moderate load produced no difference of the CFF. Some of the subjective statements paralleled this pattern, others did not. There was a significant difference between the three experimental conditions in trends of the CFF as a function of the duration of the experiments.
KeywordsNight Shift Subjective Feeling Test Situation Repetitive Activity Mental Load
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