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 punishment through the use of electric shocks, administered where 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). Murray’s character misuses the term “negative reinforcement,” which actually refers to the reinforcement of a desired behavior through the removal of an unpleasant stimulus.
- 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 main 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.