Hallucinations when the eyes are covered for several hours
In a study of the year 2004, scientists from the Harvard Medical School blindfolded a group of 13 people that they would have to stay blind for five days. Throughout these 96 hours, these people were reporting their experiences with the help of a tape recorder. The selected subjects were men and women between 18 and 35 years old with no medical history of cognitive dysfunction, psychosis or ocular pathology.
None of these people was medicated. The results indicate that the total deprivation of light over the eyes is sufficient to produce visual hallucinations in a few hours.
During this experiment, 10 of these 13 blindfolded people (77%) experienced visual hallucinations . These strange images varied in intensity and complexity, some of them consisting of simple points of light and others in figures, such as an Elvis Presley of light. In addition, none of these hallucinations made reference to past experiences, they were new images.
Subject 1 (female, 29 years old). Experience a single hallucination, 12 hours after starting to wear the bandage. It happens to be in front of a mirror, and it consists of a green face with big eyes. She is very frightened by this vision.
Subject 5 (female, 29 years old). During the first day sees circles of light, an image that will be repeated during the course of the week. On the second day she has the sensation of seeing her arms and hands moving and leaving a trail of light when she moves the real ones.
Subject 6 (man, 34 years old). Reports on numerous experienced hallucinations while listening to the Mozart's Requiem : the outline of a skull turning to stay looking at the subject. On another occasion, also listening to the Requiem, see the silhouette of someone wearing a kind of ceremonial mask and a headdress. This person has his face turned upside down and his mouth open. In a third audition of the same piece of music, he sees an older woman with a very wrinkled face and a threatening look. She is sitting in the seat of an airplane and is wearing a red eye shield similar to the one worn by people who have to protect themselves from X-rays. Then, this person's face takes on the shape of a mouse's face. Throughout the days the hallucinations continue, some of them with a stroboscopic effect.
Subject 8 (woman, 20 years). At 12 o'clock he begins to experience hallucinations suddenly. Some consist of figures that are transformed, like a butterfly that metamorphoses into a sunset, into an otter and finally into a flower. He also sees cities, lions and sunsets so bright that he "can barely look in his direction". All these hallucinations have movement. He puts a lot of emphasis on the beauty of some of these appearances: "sometimes they were much prettier than anything I've seen ... I wish I could paint."
Subject 9 (man, 27 years old). You see flashes of light during the first 24 hours. He later reports that he sees glowing peacock feathers and buildings of light.
All hallucinations ceased when the bandage was removed or a few hours later. These experiences can be explained as the result of a restructuring of the nerve connections of the brain, which tries to adapt to the lack of light. It is a process that may resemble the one that produces phantom limb syndrome in people with amputated limbs.