The Ganzfeld effect (from

German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...

for "complete field"), or perceptual deprivation, is a phenomenon of

perception Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous syste ...

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 The visual cortex of the brain is the area of the cerebral cortex that processes visual information. It is located in the occipital lobe. Sensory input originating from the eyes travels through the lateral geniculate nucleus in the thalamus ...

, and gives rise to hallucinations. It has been most studied with vision by staring at an undifferentiated and uniform field of color. 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. A flickering ganzfeld causes geometrical patterns and colors to appear, and this is the working principle for

mind machine A mind machine (aka ''brain machine'' or ''light and sound machine'') uses pulsing rhythmic sound, flashing light, or a combination of these to alter the frequency of the user's brainwaves. Mind machines can induce deep states of relaxation, conc ...

s and the dream machine. Ganzfeld induction in multiple senses is called multi-modal ganzfeld. This is usually done by wearing ganzfeld goggles in addition to headphones with a uniform stimulus. A related effect is

sensory deprivation Sensory deprivation or perceptual isolation is the deliberate reduction or removal of stimuli from one or more of the senses. Simple devices such as blindfolds or hoods and earmuffs can cut off sight and hearing, while more complex devices can ...

, although in this case a stimulus is minimized rather than unstructured. Hallucinations that appear under prolonged sensory deprivation are similar to elementary percepts caused by luminous ganzfeld, and include transient sensations of light flashes or colours. Hallucinations caused by sensory deprivation can, like ganzfeld-induced hallucinations, turn into complex scenes. William G. Braud with Charles Honorton were the first to modify the ganzfeld procedure for parapsychological use. The effect is a component of the

Ganzfeld experiment A ganzfeld experiment (from the German words for “entire” and “field”) is an assessment used by parapsychologists that they contend can test for extrasensory perception (ESP) or telepathy. In these experiments, a "sender" attempts to me ...

, a technique used in the field of

parapsychology Parapsychology is the study of alleged psychic phenomena ( extrasensory perception, telepathy, precognition, clairvoyance, psychokinesis (also called telekinesis), and psychometry) and other paranormal claims, for example, those related t ...

History

In the 1930s, research by psychologist

Wolfgang Metzger Wolfgang Metzger (born 22 July 1899 in Heidelberg, Germany; died 20 December 1979 in Bebenhausen, Germany) is considered one of the main representatives of Gestalt psychology (Gestalt theory) in Germany. Metzger's most widely acclaimed work i ...

established that when subjects gazed into a featureless field of vision they consistently hallucinated and their

electroencephalogram Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in the neocortex ...

s changed. The Ganzfeld effect has been reported since ancient times. The adepts of

Pythagoras Pythagoras of Samos ( grc, Πυθαγόρας ὁ Σάμιος, Pythagóras ho Sámios, Pythagoras the Samian, or simply ; in Ionian Greek; ) was an ancient Ionian Greek philosopher and the eponymous founder of Pythagoreanism. His poli ...

retreated to pitch-black caves to receive wisdom through their visions, known as the prisoner's cinema. Miners trapped by accidents in mines frequently reported hallucinations, visions and seeing ghosts when they were in the pitch dark for days. Arctic explorers seeing nothing but featureless landscape of white snow for a long time also reported hallucinations and an altered state of mind.

References

Vision Hallucinations

History

See also

References