Perception is everything, can you always believe your eyes? This booklet provides concise explanations of what happens with the eye and the brain to create visual effects and optical illusions. Topics covered include: dithering; pattern recognition; filling in phenomenon; borders & framing; chromatic adaption é after images; simultaneous contrast; mach band and Stroop effects. This booklet can be used across a range of subjects and levels inc. Art, Design and Science and has been compiled by the Society of Dyers and Colourists, an educational charity. Free hard copies available on request.