Experiments on flicker and some calculations on an electrical analogue of the foveal systems

Synopsis The reaction of the author's right eye to a 2° foveal flicker field has been investigated by tabulating the results of measurements of the critical flicker frequency for various illuminations and various brightness vs time functions. It is shown that, when plotting the ripple ratio r = amplitude of first Fourier component average brigthness of the stimulus versus the critical frequency f c , the average brightness being constant, the points observed with various time functions fit into one smooth curve, which at low intensities is monotonous. At high intensities the curve shows a minimum, at which r is inferior to the limiting brightness discrimination ratio, observed for f → 0. By plotting f c horizontally the curves obtained suggest an explanation of the mechanism present in the light sensitive organ and the connected nerve centres by analogy with an electric network containing a lowpass filter, a feed-back circuit and a nonlinear element transforming the physical stimulus into a number of impulses.