Time of Dark Adaptation after Stimulation by Various Brightnesses and Colors

Experiments were carried out in which an observer, previously dark adapted, was stimulated for 3 minutes by fields of various brightnesses and colors and the time required for him to become dark adapted again was measured. It was found (1)that for stimulation at 6-foot candles by equally bright fields of various colors the times to become dark adapted were about 4, 5, 7, 11, and 13 minutes for wavelengths 650, 600, 550, 500, and 450 mμ, respectively; stimulation by the ultraviolet 366 mμ line caused little disturbance to dark adaptation at the intensity used;(2)that for equally bright white and red 650-mμ stimulations at 0.1, 1, 10, and 100 footcandles, the times to become dark adapted were about 4, 5, 10, and 21 minutes for white and 3, 4, 5, and 7 minutes for red, respectively.