ESP Cards: The Zener Deck Explained, Tested and Performed

ESP cards, also called Zener cards, are a deck of 25 cards printed with five simple symbols: a circle, a cross, three wavy lines, a square and a star. They were designed in the early 1930s at Duke University to test whether people could guess unseen cards better than chance. Nearly a century later they are a party game, a classroom statistics lesson and one of the favorite props of stage mentalists.

This guide covers the history of the deck, what the famous experiments found, how to run a fair ESP card test at home, two routines you can perform with them, and which decks to buy for testing or for performing.

Best for honest tests

Zener-Style Unmarked ESP Testing Cards

A plain 25-card set with the five standard symbols, sold explicitly as unmarked and not a magic trick. That is exactly what you want when the point is a fair test rather than a performance.

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  Best for groups

  KAIU Zener Cards, 6 Decks

  Six 25-card decks in poker size, enough for a classroom or several pairs at a party.

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  Best for performing

  AIMOFAMAG ESP Cards Magic Kit

  A beginner kit of performer's ESP cards and prediction props for telepathy-style routines.

What Are ESP Cards?

ESP stands for extrasensory perception: the claimed ability to gain information without the known senses. ESP cards were created to measure that claim in a laboratory, with simple symbols that are easy to tell apart and a deck small enough to work through in a few minutes.

The Five Zener Symbols

According to accounts of the original design, the earliest decks used a rectangle that was later changed to a square. The shapes are simple geometric figures that are easy to tell apart at a glance, which keeps a run of 25 guesses quick.

Karl Zener and J. B. Rhine at Duke

The deck is named after Karl Zener (1903 to 1964), a perceptual psychologist at Duke University, who designed it with the parapsychologist J. B. Rhine in the early 1930s. Rhine used the cards in a long series of card-guessing experiments and published the results in 1934 in a book titled Extra-Sensory Perception, which was widely read for decades and made the cards famous.

From the Lab to Ghostbusters

Zener cards reached a mass audience through films and television, most famously the opening scene of Ghostbusters (1984), in which Bill Murray's character runs a far from fair ESP card test on two students. Today they are sold as games, classroom kits and mentalism props.

What the ESP Card Experiments Found

Rhine's laboratory reported subjects who scored well above chance. The best-known series, run in 1933 and 1934, involved a subject named Hubert Pearce, who was reported to average about 30 percent correct, against the 20 percent expected by chance, while the research assistant J. G. Pratt handled the cards in a different building on campus.

Why the Results Did Not Hold Up

Critics found several ways information could leak or results could be skewed without any extrasensory ability:

• Poor shuffling by hand can leave patterns that make the order easier to predict.
• The cards themselves: symbols could sometimes be read from the back of the cards through slight indentations on the backs.
• Sensory cues from the experimenter, such as facial expressions or breathing, when sender and guesser were in the same room.
• Selective reporting of good runs over bad ones.

When Rhine tightened his controls, the high-scoring subjects disappeared. The psychologist James Alcock has noted that parapsychologists no longer run card-guessing studies. The mainstream scientific position is that ESP has not been demonstrated. For a wider look at the question, read is mentalism real, and for how performers create the illusion on stage, how mentalism works.

How to Run a Fair ESP Card Test

Running your own test is a good lesson in probability and in how easily results get contaminated. These steps remove the most common leaks.

What Your Score Means

With five symbols, each guess has a 1 in 5 chance of being right, so the expected score is 5 out of 25. The probabilities below follow from the binomial distribution and assume pure guessing.

In other words, if twenty friends each do one run, someone will probably score 9 or more by chance alone. That is the single most useful thing an ESP card test teaches.

Mentalism Tricks With ESP Cards

For a performer, ESP cards are a gift: the audience already knows what they are, so a routine needs no explanation. Present them honestly as entertainment, a recreation of the old experiments where the outcome is a performance, not a scientific result. These two routines work with any 25-card deck.

1. The Symbol Prediction

2. The Two-Person Telepathy Test

A partner routine that recreates a laboratory test, with a result no laboratory ever produced: five correct out of five.

Commercial ESP Routines

Magic shops sell ESP decks and gimmicks built for performers, from marked decks to forcing decks and self-contained routines. We do not explain how they work, but the magic ESP kit in our picks below is a sensible starting point. For more props that create the same kind of mind reading effect, see the best mentalism tricks to buy, and for no-prop routines start with our guide to mentalism tricks.

The Best ESP Cards to Buy

The right deck depends on whether you want to test, teach or perform. The key question is whether the cards are plain or made for magic.

For Testing: Plain and Unmarked

An honest test needs cards that cannot be read from the back. Look for listings that say unmarked, check the backs under a bright light, and avoid magic versions.

For Classrooms and Parties: Multiple Decks

A multi-deck pack lets several pairs run tests at once and compare their scores against the chance table, which is a memorable way to teach probability.

For Performing: A Magic ESP Set

Performer's ESP cards are designed to help you, so they make routines easier and more reliable. Present them as entertainment, not as a scientific test.