Irregularities in the flicker sensitivity curve

The flicker sensitivity of the human eye may be characterized by the De Lange curve (temporal modulation transfer function plot). In the curves of two out of eight observers, D. H. Kelly [J. Opt. Soc. Am. 52,940-947 (1962)] found three peaks instead of one, as had been reported in previous publications, and suggested that they are related to the three mechanisms of color vision. Several investigations have been based on this suggestion, but there has been no confirmation of his observation. In this paper, a new measuring method was devised and the existence of the peaks was confirmed, but the hypothesis that they are related to color processes was questioned.