Psychologist Richard Gregory, British psychologist and Emeritus Professor of Neuropsychology at the University of Bristol, believed that what we see based on expectations, beliefs, prior knowledge, and past experiences. In order to test his theory, he made what is called the hollow mask experience. He used the rotation of a Charlie Chaplin mask to explain how we perceive the hollow surface of the mask as protruding based on our expectations and past knowledge.
Based on Gregory's theory, the visual information we see is combined with previously stored information about the world which we have built up as a result of our past experience. Our surroundings help to provide context to the visual information we absorb.