Ganzfeld Studies

Developed in 1971 by parapsychologist Charles Honorton, ganzfeld studies are extrasensory perception (ESP) tests (usually of telepathy) conducted with a subject who has been placed in a state of sensory deprivation so that all five senses—sight, smell, touch, hearing, and taste—are kept from any sort of stimulation. (The German word ganzfeld has been translated as “uniform field” or “entire field,” meaning “total environment.”) This theoretically allows the subject’s extrasensory perception—if it exists—to become more focused and powerful.

To bring about sensory deprivation prior to testing, the subject is most commonly put in a comfortable reclining chair within a special soundproof room that is temperature and pressure controlled for maximum comfort. The subject also wears headphones that supply white noise, which prevents the subject from hearing any other sound. Special eye covers (usually made from halved tennis balls) and lightbulbs (usually dim red ones) are used to make the subject’s eyes see a diffused light rather than a specific image.

In the earliest ganzfeld experiments, which tested for telepathy, the subject attempted to receive images from photographs that were being viewed with great concentration by a “sender,” and afterwards the researcher would ask the subject to choose which of four pictures had been transmitted. After sceptic Ray Hyman publicly attacked this methodology for making it possible for the researcher to influence the test subject’s choice, Charles Honorton changed this and other aspects of the testing so that the subject’s answers could not be influenced, intentionally or unintentionally, by the researchers’ reactions (a problem known as the Clever Hans phenomenon). This new approach, which Honorton called autoganzfeld experimentation, was later refined by parapsychologist Rick E. Berger, who also coauthored papers on ganzfeld with Honorton. Still used today, such experiments are designed so that researchers and test subjects are kept apart as much as possible, and the images used in the tests are chosen at random, nowadays by computer, from a large number of possibilities.

In repeated ESP studies using autoganzfeld experimentation, parapsychologists have found that test subjects correctly identify the image being transmitted about 35 per cent of the time, whereas, the laws of probability would only predict a 25 per cent success rate. Sceptics, however, discount these results because of the way in which successes are determined. Specifically, while being subjected to sensory deprivation, the only way a test subject can describe the image supposedly being sent telepathically is by talking about it; researchers must then determine whether and how this verbal description matches the actual photographic image seen by the sender. In many cases, several interpretations of the verbal description are possible, making the test too subjective to satisfy sceptics.


  • Charles Honorton
  • Ray Hyman
  • Telepathy


The Greenhaven Encyclopedia of Paranormal Phenomena – written by Patricia D. Netzley © 2006 Gale, a part of Cengage Learning

Related Articles

Honorton, Charles

Charles Honorton (1946–ca. 1992) Parapsychologist Charles Honorton is best known for two accomplishments: his experiments designed to discover whether dream content could be transferred from…

Hyman, Ray

Hyman, Ray (1928– ) An outspoken critic of experiments that seem to show that extrasensory perception (ESP) is a real phenomenon, skeptic Ray Hyman has…

Zener cards

Designed by Dr. Karl Zener during the 1930s for psychologist J.B. Rhine, Zener cards are used to test the Extrasensory Perception (ESP) ability known as…


Telepathy is the mind-to-mind communication of thoughts, ideas, feelings, and mental images. In Psychical Research, Paranormal Investigation, and Mediumship, telepathy is considered as a potential…