Ganzfeld Effect

The ganzfeld effect, named from the German for complete field, is a perceptual phenomenon that occurs when a person is exposed to a uniform, unstructured field of stimulation, such as staring at a featureless, evenly lit surface. Because the visual system receives no changing signal to process, the brain appears to amplify its own internal neural noise while searching for the visual information it is not receiving, which can produce hallucinations or an experience of the visual field appearing to go dark, as though the person had become temporarily blind. The psychologist Wolfgang Metzger conducted pioneering research on the effect in the 1930s, finding that subjects who stared into a featureless visual field reliably reported hallucinations, accompanied by corresponding changes on an electroencephalogram. Related reports of altered perception in prolonged, unstructured sensory environments include historical accounts from miners and Arctic explorers surrounded by unbroken darkness or featureless snow, and researchers William Braud and Charles Honorton later adapted the ganzfeld procedure as an experimental method within parapsychological research into extrasensory perception.