The neural determination of critical flicker frequency.

Abstract

Both by using the usual method for obtaining critical flicker frequencies on humans, and by use of intermittent light on rabbits and recording action currents from the animals'' cerebral cortices it was found that uniformity of sense-cell discharge was not necessary for sensory uniformity. Single sense-cell discharges were able to set into motion the necessary nervous activity to bring about sensory continuity over many msecs. With flashes occupying most of the flicker cycle, flicker was produced when a slight extension of the dark interval allowed a slight "off" response to occur. "Off" responses probably occurred in sense-cells other than those responding to positive stimulation. The primary physiological conditions responsible for "fusion" or. uniformity were apparently beyond the retina in such cases.