illusions are pictures or objects that switch between the alternative interpretations. The Necker cube is a well known example; another instance is the Rubin vase. Distorting or geometrical-optical illusions are characterized by distortions of size, length, position or curvature. A striking example is the Café wall illusion. Other examples is the famous Müller-Lyer illusion and Ponzo illusion.Paradox illusions are generated by objects that are paradoxical or impossible, such as the Penrose triangle or impossible staircases seen, for example, in M. C. Escher's Ascending and Descending and Waterfall. The triangle is an illusion dependent on a cognitive misunderstanding that adjacent edges must join. Fictions are when a figure is perceived even though it is not in the stimulus. To Serve Man is an episode of the television series The Twilight Zone Based on a short story by Damon Knight The title is a play on the verb serve which has a dual meaning of to assist and to provide as a meal it is considered a classic and where I got the idea for howgoogleservesman.com