Psychosomatic Medicine 4:369-375 (1942)
© 1942 American Psychosomatic Society

A Factor in Visual Fatigue

¹ Washington University School of Medicine, Laboratory of Neurophysiology, Saint Loius

Two situations of antagonistic eye muscles were studied. One set involved the pupillary mechanism, the other the extrinsic eye muscles. For the former, the stimulation represented repeated shifts from dark to light calling for repeated dilatation and constriction. Up to a certain rate of repetition the pupil mechanism was able to follow the stimulus changes through the usual pattern of reciprocal innervation and movement, but beyond a certain point this shifted into over-lapped or simultaneous innervation and contraction, producing an uncomfortable and fatiguing result.

For the extrinsic muscles, a contrasted black and white field stimulus situation and a "simple" but difficult task were set up to study reciprocal action also. The conflicts produced appeared to have many of the same characteristics as those demonstrated in the action of the pupillary muscles. The conflicts in both cases were taken to be basic examples in the cause of discomfort and fatigue.

Note:
¹ Work done under grants from the Committee on Scientific Aids to Learning, National Research Council; and the Rockefeller Foundation.