EFFECTS OF PUPIL APERTURE AND OF THE TIME OF EXPOSURE ON THE FATIGUE INDUCED VARIATIONS OF THE FLICKER FUSION FREQUENCY

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Abstract
Changes in Flicker Fusion Frequency (CFF) following performance of a mental task were measured on seven subjects using both an artificial pupil and normal vision, in order to see if these changes are due to modification of the pupil aperture following mental fatigue. Variations of CFF following a mental task were also studied in relation to the duration of the measures needed to establish CFF. Thirdly, the influence of an interruption of the intermittent light between two measures of CFF was examined. The results show that (1) the artificial pupil lowered the CFF but did not influence its changes due to the mental task ; (2) lengthening the duration of measurement from 10 to 16 sec lowered the CFF and partially masked the effect of mental fatigue ; (3) the interruption of the intermittent light between two measures did not alter the CFF values significantly. Replication of the measures on different days revealed a significant practice effect in that the CFF rose on the second day.