Retinal Responses to Intermittent Light of Subfusional Frequencies

Abstract

The effect of intermittent lights of subfusional frequencies was investigated by the method of electrostimulation of the eye. The lightdark ratio of flickering light was always 1 :1.
1. Increases of electrical sensitivity following an illumination with intermittent white light were usually greater below the CFF than above it. When the electrical sensitivity after an illumination was plotted against the rate of flicker of the illuminating light, the curve showed two prominent maxima at about 10 and 20 cps.
2. The same effect could be seen when monochromatic lights of various wave-lengths were used instead of white light. 3. At the flicker rate of 10 cps., the degree of enhancement of electrical excitability was found highest for red light, intermediate for green light, and lowest for blue light.
4. The rod-process received no such conspicuous enhancement as the cone-processes.
5. The above-mentioned effect was correlated with the psychological phenomenon described by Bartley that a light flickering at a subfusional rate looks brighter than a fused one. Based upon the wave- length de-pendence of this phenomenon a retinal mechanism was suggested for photic activation of seisure waves with intermittent stimulation.