Effects of Repetitive Tasks with Different Degrees of Difficulty on Critical Fusion Frequency (CFF) and Subjective State

Critical Fusion Frequency (CFF) and subjective state assessed by questionnaires were determined on 18 subjects during three different types of repetitive tasks of three hours duration. The three types of repetitive tasks were characterized by different degrees of difficulty. In the task with the low degree of difficulty, CFF showed a marked decrease and the subjective state revealed changes in the sense of an impairment. The same changes, less pronounced but still characteristic, were seen in the task with the high degree of difficulty. On the other hand, both parameters showed minimal changes in the task with the moderate degree of difficulty.