Visual hallucinations during prolonged blindfolding in sighted subjects

The authors report the occurrence of visual hallucinations of varying complexity in 13 normal subjects after sudden, complete, and prolonged visual deprivation. The subjects were all healthy individuals with no history of cognitive dysfunction, psychosis, or ocular pathology. They wore a specially designed blindfold for a period of five consecutive days (96 hours) and were asked to record their daily experiences using a hand-held microcassette recorder. Ten (77%) of the subjects reported visual hallucinations, which were both simple (bright spots of light) and complex (faces, landscapes, ornate objects). The onset of hallucinations was generally after the first day of blindfolding. Subjects were insightful as to their unreal nature. These results indicate that rapid and complete visual deprivation is sufficient to induce visual hallucinations in normal subjects.