Effects of Field Brightness on an Induced Negative After-image Phenomenon

IF a coloured stimulus, a white stimulus, and relative absence of stimulus are repeatedly presented in that order for 0.017, 0.10 and 0.083 sec respectively, there are values of stimuli brightness at which only the complement of the coloured stimulus is perceived. This effect, first reported by Bidwell in 1897 1 , has facilitated investigations of after-images; the decision as to which of two complementary colours is seen is more accurately made than are decisions as to the colour, intensity, or duration of afterimages. The study of induced negative after-images is of interest, as these phenomena depend on the relation between excitatory and inhibitory retinal reaction and may be used in physiological and pharmacological studies.