Brightness Variations in Stimuli with Ramp-Like Contours*

摘要: Perceived brightness was measured at several points on stimuli bounded by luminance ramps. As the ramps widen, perceived contrast between stimulus and background decreases, although objective is unaffected. The rate of decrease varies from one part to another, complex variations in brightness, including Mach bands, occur. A von Bekesy-type model accounts for many features data.