Visual acuity in light of different colours

Abstract

The problem studied in this paper is the poor visual acuity in light of short wave lengths. It seems to have been tacitly assumed that the poor acuity was due to insufficient brightness of "blue" light. This problem has been examined by varying the intensities of the lights used (narrow regions of spectrum by color filters) and by comparing the threshold values. The conclusion is that there is something special about the stimulation by light of short wave lengths as shown by the poor acuity. The relation of brightness to intensity is known to follow a different law for short from that for long wave lengths and these 2 facts point to a special type of receptor which may be the rods.