Study participants sat in a padded chair in the middle of an anechoic chamber, a room designed to dampen all sound and block out light. The researchers describe the set-up as a "room within a room," with thick outer walls and an inner chamber formed by metallic acoustic panels and a floating floor. In between the outer and inner walls are large fiberglass wedges. "This results in a very low noise environment in which the sound pressure due to outside levels is below the threshold of hearing," the researchers wrote.
Among the nine participants who scored high on the first survey, five reported having hallucinations of faces during the sensory deprivation, and six reported seeing other objects or shapes that weren't there. Four also noted an unusually heightened sense of smell, and two sensed an "evil presence" in the room. Almost all reported that they had "experienced something very special or important" during the experiment.
The researchers were not altogether surprised by such dramatic results from only 15 minutes of sensory deprivation. Although few scientists are studying sensory deprivation today, a small body of research from the 1950s and 1960s supports the idea that a lack of sensory input can lead to symptoms of psychosis. "Sensory deprivation is a naturalistic analogue to drugs like ketamine and cannabis for acting as a psychosis-inducing context," Mason wrote, "particularly for those prone to psychosis."
"Very few of the subjects devolved into apes and became one with the Godhead", the researchers did not say.