Mach Band Attenuation by Adjacent Stimuli
Mach bands are illusory bright and dark bands seen where a luminance plateau meets a ramp, as in half-shadows or penumbras. Ratliff, Milkman, and Kaufman (1983) showed that Mach bands are attenuated by placing stimuli, such as bars, nearby. An experiment comparing Mach band attenuation for bar and Craik-O'Brien stimuli shows that they are equally effective in attenuating Mach bands. The results suggest that the high-frequency components of a stimulus adjacent to a ramp are responsible for the attenuation. Thc findings are interpreted in terms of a recent filling-in model of brighness perception and the results of computer simulations of stimuli used by Ratliff et al and the present experiment are shown.