In a 2004 study, scientists from the Harvard Medical School blindfolded a group of 13 people they would have to go blind for five days. Throughout these 96 hours, these people reported on 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 dysfunctions, psychosis or ocular pathology.
None of these people took medication. The results indicate that total deprivation of light on 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 of figures, such as an Elvis Presley of light. Furthermore, none of these hallucinations referred to past experiences, they were new images.
Subject 1 (female, 29 years old). You experience a single hallucination, 12 hours after you start wearing the bandage. It occurs while in front of a mirror, and consists of a green face with large eyes. She is very frightened by this vision.
Subject 5 (female, 29 years old). During the first day you see circles of light, an image that will be repeated throughout 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 actually moves them.
Subject 6 (man, 34 years old). Report numerous hallucinations experienced while listening to the Mozart Requiem: the outline of a skull turning until it is looking at the subject. On another occasion, also listening to the Requiem, he sees the silhouette of someone wearing a kind of ceremonial mask and a headdress. This person has their face turned upside down and their mouth is 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 on the seat of an airplane and wears a red eye shield similar to the one that people wear who have to protect themselves from X-rays. This person’s face then takes the shape of the face of a mouse. Throughout the days the hallucinations continue, some of them with stroboscopic effect.
Subject 8 (female, 20 years old). At 12 o’clock he suddenly begins to experience hallucinations. Some consist of figures that transform, 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 their direction.” All these hallucinations have movement. He puts a lot of emphasis on the beauty of some of these appearances: “sometimes they were much more beautiful than anything I have seen … I wish I could paint.”
Subject 9 (man, 27 years old). See flashes of light for 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 nervous connections of the brain, which tries to adapt to the lack of light. This is a process that can resemble that of phantom limb syndrome in people with amputated limbs.