Ultimate Eye Twisters

Gianni A. Sarcone and Marie-Jo Waeber are co-founders of Archimedes' Laboratory, an Italian-based training and consulting network of game designers that specialises in developing creativity. They invent, create and develop interactive thinking games and optical illusions.

• Double trouble: images that appear to be two or more different objects or people • Impossible People: illusions involving people and faces • Artful animals: illusions involving animal images. Camouflage, hidden animals etc • Colours and Shapes: Colour adaptation illusions – studying one image before looking at another causes odd things to happen to colour perception • Twisted!: Shape puzzles. Line puzzles. Straight or curvy? How long? Which line? How far away? • Moving patterns: illusory moving patterns: You know these pictures aren't moving – but somehow it looks as if they are! • Visual Paradoxes: Paradoxical illusions: curious perception puzzles • Impossible Images: Escher prints and other images of buildings and shapes that would be impossible in three dimensions • Seeing Double: Classic images with two interpretations – old woman or young woman? Face or basket of fruit • Afterimages: Stare at the discoloured image for 30 seconds, close your eyes, and a photo-quality face appears on your eyelids • Twisted!: Shape puzzles. Line puzzles. Straight or curvy? How long? Which line? How far away? • Psychedelic Twisters: Bright swirls and jags of colour that look as if they're moving when they aren't • Forced Perspective: Do Try This at Home!: Examples and ideas for creating your own optical illusions by setting up photos which show you, for example, holding a plane between your fingers as it flies through the sky.