ESP means "Extra Sensory Perception." The meaning is clear: obtaining knowledge via means not associated with our normal senses. Such things are also known as "psi" phenomena. The Greek letter Psi is used for this. ESP comes in various forms.
  • Clairvoyance or Remote Viewing; seeing at a distance
  • Precognition; seeing things in the future
  • Psychokinesis; producing physical effects by thinking
  • Telepathy; mind reading, thought transfer
  • ...

Clifford Pickover ESP Experiment


A Princeton Lab on ESP Plans to Close Its Doors

Zener Cards

By the way, Zener cards are named for Swiss psychologist Dr. Karl Zener (1903-1963) who developed the cards for J.B. Rhine's ESP tests.

Scene from "Ghostbusters"

Two Scenes from "Columbo Goes to the Guillotine"

    Profs Scalise and Cotton demonstrated an ESP test using the classic Zener cards. Prof. Cotton "transmitted" and Prof. Scalise "received." His ESP was really working? Or was it??

    We discussed how this might be done. The class has a challenge: figure out a way to duplicate the performance. If you can figure out something, you are encouraged to demonstrate it in class. Actually, several class members correctly figured out how it was done.

    We did an all-class experiment with Zener cards. Prof. Cotton "transmitted" to everyone in the class. There were 5 trials. Each one wrote down what they "received" from Prof. Cotton. At the end we wrote the transmitted sequence on the blackboard and asked for a show of hands to find out how many got none right, one right, two right, and so on. Compare the class results to the calculated probabilities. Remember - these are the probabilities for random guessing. You can see that nobody got more than 4 correct, and the overall distribution fits the probabilities rather nicely. It is not impossible that someone might get 5 correct, but it would be rare.

    # Right    Class     Theoretical
       0    25/54=0.463    0.328
       1    21/54=0.389    0.410
       2     8/54=0.148    0.205
       3     0/54=0.000    0.051
       4     0/54=0.000    0.006
       5     0/54=0.000    0.0003

    Our result is consistent with random guessing. There is no need to invoke ESP to explain the result. We had a few more get none right than 1 right, which is slightly different from chance. Nobody got more than 2 right. Looks like no ESP here.

    One last practical consideration: why aren't psychics and astrologers fabulously wealthy? Anyone who can REALLY foresee the future accurately could make a killing in the stock market.


    We will explore experiments for testing ESP. The goal is a well-controlled test which will positively demonstrate the effect if it exists. The experiment must achieve this: if the claimant really can perform the ESP phenomenon, then they will be able to to do so easily, but, if they are relying on any kind of trickery, the attempt will fail. Far too many ESP experiments have been discredited because of failure to achieve the second goal. Here are some VERY good notes in The Skeptic's Dictionary.

    In ANY test of "psychic powers", the experiment must account for the fact that psychics can be very slippery. James Randi requires that all psychics who attempt to win his million-dollar prize agree IN ADVANCE to ALL experimental conditions and exactly what constitutes success and failure, then sign a contract including all of this. As mentioned before, in pseudo-science all failures must be explained away so no doubt will be cast on the claimed power. Failure can be blamed on "negative energy" emitted by skeptics, confusing objects in the room, time of day, or anything creative that can be invented quickly to explain a failure. See The Skeptic's Dictionary for notes on the ad hoc excuse.

    James Randi offers a million dollars to anyone who can PROVE they have ESP under controlled conditions. Although some number have tried, Randi's money is still safe.

    James Randi understands perfectly that the test protocol must be written to prevent all forms of trickery and ad hoc excuses for failure. You might be surprised to hear that the person best equipped to prevent trickery is a magician, not a scientist. The magician's art is that of trickery and deception, things that a scientist does not expect. In science, one is expected to be clear and honest, describing all experiments and data with great clarity and NO trickery.

Moon Mission ESP Test

    Astronaut Ed Mitchell conducted an unauthorized ESP test on the Apollo 14 moon mission. He tried to "transmit" Zener card images to "receivers" on Earth, 150,000 miles away. The idea was to do it on the return flight during the time that he would have to rest between work periods. The experimental group had prearranged a time for the experiment, and, when the appointed time arrived, the receivers began working. This was to be a test of telepathy, or mind-to-mind transmission. Unfortunately for the experiment, Mitchell was delayed by the workload and started his "transmission" about one hour late. This converted the experiment from telepathy to precognition. Out of 200 attempts, the four "receivers" got 51 correct. Chance predicts about 40, but 51 is not significantly better than 40. See James Randi's notes for more on the subject.


    Now for dowsing - the claimed ability to find water using a very simple device. A dowser might use a forked stick, a pendulum, brass rods, or other item. They claim that the device responds to the presence of water by bending, swinging differently, or moving in some specific manner. James Randi offers a million dollars to anyone who can PROVE they can do this under controlled conditions. Although some number of dowsers has tried, Randi's money is still safe; no dowser has yet succeeded.

    James Randi once tested a dowser who claimed the ability to find metal by using his dowsing rod. A test was set up where a piece of metal was placed in one of several non-metallic containers and the lids put on. In a warm-up test, the dowser's rod correctly indicated which container had the metal, but the dowser knew in advance which container held it. In the real test, the dowser did not know which container had the metal, and he failed to locate it. An ad hoc excuse quickly followed. Randi then removed the cloth covering the test table, which was made of metal! The dowser had completely failed to detect the metal table. Test failed. For more on dowsing, see James Randi's library page. Here's another good page describing protocols for testing dowsers. Once again, The Skeptic's Dictionary has an excellent description. Here's an EXCELLENT description of a dowsing test done in Australia.