Zener cards are cards used to conduct experiments for extrasensory perception (ESP), most often clairvoyance. Perceptual psychologist Karl Zener (1903–1964) designed the cards in the early 1930s for experiments conducted with his colleague, parapsychologist J. B. Rhine (1895–1980).
The Zener cards were a deck made up of five simple symbols. The five different Zener cards are: a hollow circle (one curve), a Greek cross (two lines), three vertical wavy lines (or "waves"), a hollow square (four lines), and a hollow five-pointed star. There are 25 cards in a pack, five of each design.
In a test for ESP, the person conducting the test (the experimenter) picks up a card in a shuffled pack, observes the symbol on the card, and records the answer of the person being tested for extrasensory perception, who would guess which of the five designs is on the card in question. The experimenter continues until all the cards in the pack have been tested. Poor shuffling methods can make the order of cards in the deck easier to predict. The cards could have been marked and manipulated. In his experiments, J. B. Rhine first shuffled the cards by hand but later decided to use a machine for shuffling.
Rhine's experiments with Zener cards were discredited due to the discovery that sensory leakage or cheating could account for all his results such as the subject being able to read the symbols from the back of the cards and being able to see and hear the experimenter to note subtle clues. Terence Hines has written:
The methods the Rhines used to prevent subjects from gaining hints and clues as to the design on the cards were far from adequate. In many experiments, the cards were displayed face up, but hidden behind a small wooden shield. Several ways of obtaining information about the design on the card remain even in the presence of the shield. For instance, the subject may be able sometimes to see the design on the face-up card reflected in the agent’s glasses. Even if the agent isn’t wearing glasses it is possible to see the reflection in his cornea.
Once Rhine took precautions in response to criticisms of his methods, he was unable to find any high-scoring subjects. Due to the methodological problems, parapsychologists no longer utilize card-guessing studies.
If the null-hypothesis (no psychic ability) is assumed and each card selected for testing is chosen in a truly random fashion, a user's success ratio is expected to approach 20% (1 hit per 5 trials) as their number of trials increases. The further the observed scenario is from the expected scenario, the more cause for believing the null-hypothesis is not true (the results are not simply due to chance).
Popular culture reference
- "The Schizoid Man" episode (1967) of the British science fiction-allegorical television series The Prisoner has plot elements that hinge on the use of Zener cards.
- In a humorous scene depicted in the movie Ghostbusters (1984), Dr. Peter Venkman (Bill Murray) conducts a clairvoyance experiment using Zener cards and negative reinforcement through the use of electric shocks, administered if the subject failed to demonstrate clairvoyant abilities (i.e., the subject would avoid the electric shock if he was clairvoyant and thus said the correct symbol). It was biased from the start, however, as he had two subjects, one female and one male. Dr. Venkman always let the female subject off, even if she was incorrect, incessantly shocking the male subject. (Venkman's use of the term "negative reinforcement" is a mislabel, as it properly refers to the removal of an unpleasant stimulus. Venkman's electric shocks would more correctly be termed punishment by experimental psychologists.)
- In the beginning of Ghostbusters: The Video Game, Slimer (the Ghostbusters live-in science experiment, or ghost subject) is attempting to guess the Zener card with three wavy lines, but he must have guessed it wrong, because when the ghost sees the card, he frustratedly throws all the cards in the air and tries to look for the certain card he was looking for.
- These cards are also used in the film The Gift.
- In Star Wars: Episode I – The Phantom Menace (1999), (as a reference to Zener cards) a young Anakin Skywalker, in an interview with the Jedi Council, had to perceive (in a clairvoyance-like test) a device that projected images on a monitor held by Mace Windu, in order to examine the power and control of Anakin's Force-wielding abilities.
- In the video game The World Ends With You, Shiki Misaki, a partner of the protagonist, Neku Sakuraba, uses Zener cards to attack enemy 'Noise'.
- Witch house band ∆AIMON named their song '○+☆≋□' after Zener cards in their 2011 release Amen EP.
- In the video game Beyond: Two Souls, Aiden, a supernatural entity, assists a young Jodie in identifying which Zener card is picked during a scientific testing sequence.
- These cards are also used in the film The Fury.
- The markings on the Pokémon Kadabra's body—the star and the three wavy lines—come from the Zener cards.
- In the anime Kotoura-san, specifically episode 6, "Summer Vacation!" ["Natsuyasumi!" (夏休み!)], during a mention of Psychic research in an abandoned building, one can see the use of Zener cards by a test subject.
- "Psi Power", a song by the British space-rock band Hawklords from their album 25 Years On (1978), describes a school youth being tested for psychic abilities with symbols from Zener cards: circle, square, triangle, and wave.
- In Thomas Pynchon's 1970s novel Gravity's Rainbow, Zener cards are referenced as one of many forms of psychological enquiries undertaken by protagonists of "The Firm".
- In the video game Urban Legend in Limbo, the psychic Sumireko Usami carries Zener cards and uses them as an attack.
- In the video game Mario Tennis: Power Tour, the minigame Instinct Drill, used to train the player's ESP, is a memory game that uses the Zener cards.
- In the animated series My Little Pony: Friendship Is Magic episode "The Show Stoppers", the Cutie Mark Crusaders test whether Apple Bloom is clairvoyant with a deck very similar to Zener cards. Clairvoyance is one of the many possibilities they think of for a presentation on a talent show.
- "Zener Cards". Glossary of Skepticism & the Paranormal. About.com. Retrieved 2006-12-20.
- Terence Hines. (2003). Pseudoscience and the Paranormal. Prometheus Books. p. 115
- Matt Jarvis, Julia Russell. (2002). Key Ideas in Psychology. Nelson Thornes Ltd. p. 117
- Carroll, Todd (2006-02-17). "Zener ESP Cards". The Skeptic's Dictionary. Retrieved 2006-07-18.
- John Sladek. (1974). The New Apocrypha: A Guide to Strange Sciences and Occult Beliefs. Panther. p. 174 "It's astonishing that playing cards should have been chosen for ESP research at all. They are, after all, the instrument of stage magicians and second-dealing gamblers; they can be marked and manipulated in many traditional ways. At the best of times, card-shuffling is a poor way of getting a random distribution of symbols."
- Massimo Pigliucci. (2010). Nonsense on Stilts: How to Tell Science from Bunk. University of Chicago Press. pp. 80-82
- Jonathan C. Smith. (2009). Pseudoscience and Extraordinary Claims of the Paranormal: A Critical Thinker's Toolkit. Wiley-Blackwell. ISBN 978-1405181228. "Today, researchers discount the first decade of Rhine's work with Zener cards. Stimulus leakage or cheating could account for all his findings. Slight indentations on the backs of cards revealed the symbols embossed on card faces. Subjects could see and hear the experimenter, and note subtle but revealing facial expressions or changes in breathing."
- Terence Hines. (2003). Pseudoscience and the Paranormal. Prometheus Books. pp. 119-120
- Milbourne Christopher. (1970). ESP, Seers & Psychics. Thomas Y. Crowell Company. p. 28
- James Alcock. (2011). Back from the Future: Parapsychology and the Bem Affair. Skeptical Inquirer. "Despite Rhine’s confidence that he had established the reality of extrasensory perception, he had not done so. Methodological problems with his experiments eventually came to light, and as a result parapsychologists no longer run card-guessing studies and rarely even refer to Rhine’s work."