2. "A visual effect seen under the influence of LSD". --Henry W.Targowski (in Mark/Space , 1995).
3. "In perception, the visual after-effect produced by focusing on an object and then looking at a blank surface. It usually appears in a colour complementary to the original and obeys Emmert's Law to the effect that its apparent size varies in direct proportion to the apparent distance of the surface against which it is cast". --Jerome S.Bruner (in The Fontana Dictionary of Modern Thought , 1977).