It happens to all of us. Sometimes, we imagine something, that is not real. Called hallucination, it is a perception in the absence of external stimulus that has qualities of real perception. Hallucinations are vivid, and are perceived to be located in external objective space.
But why we hallucinate? What happens when we hallucinate? Oliver Sacks, a neurologist, links hallucination with the Charles Bonnett syndrome. That is when visually impaired people experience lucid hallucinations.
Oliver talks about the experiences of his patients in heartwarming detail and walks us through the biology of the phenomenon.