title: The nonequivalence of abrupt and diffuse illusory contours.
abstract: A distinction is drawn between diffuse regions of apparent brightness and illusory, but abrupt, brightness gradients. Differences between the two phenomena are sufficient to disqualify conclusions about one based on observations about the other. It is suggested that diffuse contours may be attributable to peripheral mechanisms while sharp contours may be central or cognitive in origin.
mesh_terms: D000328:Adult; D004193:Discrimination Learning; D005260:Female; D005556:Form Perception; D006801:Humans; D007088:Illusions; D008297:Male; D009903:Optical Illusions; D010466:Perceptual Closure; D014796:Visual Perception