ABSTRACT
The world around us seems concrete and immediate, and our ability to perceive it is easily taken for granted. Objects have positions, shapes, and colours that seem to be perceived instantly, and we can reach for them or move to where they are, without any apparent effort. Clearly, there must be some process that gives rise to visual experience, and it is not surprising that throughout history people have found it fascinating. If what we perceive is what we take to be true or factual about the world, are everyone's experiences the same? What is the perceptual world of animals, or infants, like? What sorts of errors do we make in perceiving? Can perceptual experience be communicated to others? Philosophers, artists, physicians, and, more recently, psychologists have tried to find ways to answer such questions, which are among the most fundamental that can be posed about the human mind.
