The role of albedo and contrast in a test of selective attention

The operation of a selective process was demonstrated under conditions that eliminated exploratory behavior, receptor adjustments, and that could not be construed as abstraction. Ss were given a choice reaction-time test to tachistoscopically exposed stimuli. There were three conditions of brightness and contrast. Four targets equally spaced in brightness units were presented either on a black, a medium gray, or a white background. If a selective process was found to operate, it was hoped to separate the effects of albedo and contrast as factors determining priority in selection. The results confirmed that Ss chose the stimuli of highest contrast, but in the event that contrast was equivalent for two stimuli, the target of highest albedo was chosen significantly more often.