A Comparison of Electrical and Psychophysical Determinations of the Spectral Sensitivity of the Human Eye

Abstract

Electrical responses of the human retina have been measured by the use of an electrode mounted on a contact lens. The form and magnitude of such responses have been determined for stimulation by filtered lights having various dominant wave-lengths. Two sets of spectral sensitivity data, one for the dark-adapted eye and the other for the light-adapted, have been obtained by computing the intensity of stimulation necessary at each wave-length to arouse an electrical response of a given small magnitude. Comparable data have been obtained in psychophysical experiments in which the same filter combinations and closely similar methods of computation have been employed. The electrical data, for both the light-adapted and the dark-adapted eye, agree much more closely with the psychophysically determined scotopic sensitivity curve than with the photopic. It appears, however, that lights of the shorter wave-lengths are somewhat more effective in arousing electrical responses than the scotopic sensitivity curve would predict.