Ganz

The Ganzfeld effect, or perceptual deprivation, is a phenomenon of perception caused by exposure to an unstructured, uniform stimulation field. The effect is the result of the brain amplifying neural noise in order to look for the missing visual signals. The noise is interpreted in the higher visual cortex, and gives rise to hallucinations. It has been most studied with vision by staring at an undifferentiated and uniform field of colour. The visual effect is described as the loss of vision as the brain cuts off the unchanging signal from the eyes. The result is “seeing black”, an apparent sense of blindness.