Three experimental techniques show that the contrast of chromatic and achromatic negative afterimages of stabilized gratings depends linearly on the conditioning contrast over a wide range (0-90%), and that both types of afterimage have similar gains across spatial frequency. They also have similar time-courses of buildup and decay along exponential curves with a (1/e) time constant between 4 and 8 sec. Both chromatic and achromatic afterimages greatly increase the detection threshold of a grating briefly flashed upon the afterimage if the flashed grating is chromatic and isoluminant; however, if the flashed grating is achromatic, its threshold is practically unaffected by either type of afterimage.
