Adaptation effects on the apparent "squareness" of square-wave gratings.
Adaptation to a 9 cycles deg-1 sine wave makes the apparent brightness profile of a 3 cycles deg-1 square wave look less "square" even when it  does not look like that of a sine wave. Adaptation to a 3 cycles deg-1 sine wave has no noticeable effect. Hypotheses based on "excitation patterns" across spatial-frequency-selective channels can account for these results; it is not clear whether variations in local light adaptation can also account for them.
D000221:Adaptation, Ocular; D004193:Discrimination Learning; D005556:Form Perception; D006801:Humans; D007088:Illusions; D009903:Optical Illusions