The Theory of the Visual Threshold

Abstract

The complete range of data relating the visual intensity threshold to the exposure time can be quantitatively accounted for, with homogeneous measurements, in terms of the theoretical deduction that the reciprocal of the threshold intensity, I/[DELTA]Io, gives a probability integral in terms of log t. II. The kinetics of dark adaptation, as expressed in the change of intensity threshold with dark time, displays the statistical results of fluctuating recovery of excitability as regards the elements of neural effect produced from excited units with variable thresholds. The form of the dark adaption contour does not reveal the physiochemical nature of the metabolic process governing receptor excitation.