Imagine horses that turn into frogs. Skull's eyes morphing into dainty ladies. Dragons twisting into elephants. Sound like the latest digital effects? Guess again. Seeing Double is a collection of more than 175 seductive and mind-bending illustrations that trick the eye into seeing two different images -- and never both at the same time! And once you’ve seen them both, it is impossible to focus on just one, as the other will keep "popping" into your consciousness. Exquisitely rendered hand drawn images, both antique and contemporary, from around the world fill every page of this delightfully entertaining, full-color volume. Double illusions, upside-downs, ambiguous images and ambigrams are smartly organized by technique and illusory effect, with vivid descriptions of the psychological impact the artist intended as well as current scientific explanations for each stunning effect. In creating these playful twosomes, the artist may paint a single line that is the chin of one man, the nose of another or strike an unusual equilibrium between a shape and its background, teasing our usual sense of perception. Psychologist and collector, J. Richard Block has put his life’s work, his enthusiasm, and his knowledge into this wonderfully fun, informative treasure trove of puzzles, illusions and double diversions.