States of Mind

Episode 3: Richard Gregory

March 6, 1983

Until the present century vision was often regarded as a simple process - the eyes provide the brain with pictures of the outside world, and the brain just looks at them. We now know that visual perception is one of the most complicated functions that the human brain performs. Professor Richard Gregory, from the University of Bristol, shows how the study of illusions has demonstrated how much of what we see ' out there' is actually generated from within.