Extrasensory perception, abbreviated ESP, describes a way of communicating or of being aware of something without using the known senses. An awareness of another person’s thoughts without the use of sight, hearing, taste, touch, or smell would be an example of ESP. The study of extrasensory perception is part of the field of psychology called parapsychology.
What parapsychologists study.
Extrasensory perception is commonly divided into three kinds of phenomena—(1) telepathy, (2) clairvoyance, and (3) precognition. Telepathy is the sensing of a person’s thoughts or feelings in some unknown way. Clairvoyance is an awareness of objects, events, or people without the use of the known senses. Precognition is knowledge of a future event by unknown means. Some parapsychologists also study phenomena related to ESP, such as psychokinesis. Psychokinesis is the mental control of physical objects, such as influencing the fall of dice.
Early ESP research.
Classic ESP experiments, which were developed and used mainly between the 1930’s and the 1960’s, involved card guessing. Researchers often used a deck of 25 special ESP cards (also called Zener cards, named for the American psychologist Karl E. Zener). Each Zener card had one of five symbols on it, such as a circle or a plus sign. In a simple test of telepathy, a person called the sender would randomly draw a card from a shuffled deck and concentrate on its symbol. A second person, called the receiver, usually sat in another room and would try to name the symbol that the sender was thinking of. In an experiment on clairvoyance, the sender would take cards from the deck one at a time but would not look at the symbols, and the receiver would try to name them. In a test for precognition, the cards would be selected after the receiver made a guess.
Modern ESP research.
ESP researchers improved their experiments in many ways by the 1970’s and 1980’s. Senders now usually view photographs or short scenes from a movie instead of Zener cards. The receiver is then told that the sender is looking at a photograph or movie scene and is asked to describe it, without being given any other information. Experimenters take many precautions so that all known ordinary explanations for successful guessing can be ruled out. For instance, it is inappropriate for people who know the correct answer to be present in the room when a receiver is attempting to describe a photograph because they might convey subtle, unconscious clues about the answer.
Modern ESP experimenters analyze their results using statistical methods. These methods compare the actual results to what would be expected if the receiver were just guessing and not using ESP. In the most basic method of analysis, the actual target photograph and three additional “decoy photographs” are shown to the receiver. The receiver is asked which one he or she thinks the sender was trying to send. By chance, receivers should pick the correct photograph about one-fourth of the time. However, many modern ESP studies have found that receivers do so about one-third of the time. One important detail is that a computer selects the actual target photograph at random from the four possible choices. With this computer-generated random selection, the success of the receiver cannot be easily explained by the sender and receiver coincidently choosing the same photograph.
Since the 1970’s, universities and laboratories have conducted thousands of scientific ESP experiments. The success rate of about one-third has remained consistent. To some, this rate provides strong statistical evidence that the results are not due to chance. However, many scientists are reluctant to accept that these experiments provide evidence for ESP. Many believe that the existence of ESP would require a change in thinking about the fundamental laws of physics. Current theories in physics do not provide an explanation for how ESP can exist. Other scientists disagree, citing various advances and modern theories in physics as possible explanations for ESP. The existence of ESP will remain controversial until a scientific explanation is found for how it works.
Possible misunderstandings.
Some scientists point out that the evidence for ESP is controversial because many personal experiences that appear to be the result of ESP can be explained by psychological processes of which most people are not aware. People often do not know how events around them set off their thoughts. Two people who know each other well may both experience a similar chain of thoughts when exposed to a common stimulus. For example, a husband and wife may be reading together and not paying much attention to music on a radio. Then certain music triggers in each of them the memory of a person they met several years ago but have not encountered since. Just as one of them is about to bring up the person’s name, the other one mentions it. These similar thoughts may seem to be an instance of extrasensory perception. Neither person may realize that the music actually set off both of their thoughts. Other experiences that seem to involve ESP may, in fact, be simple coincidences. Everyone will likely experience improbable events that seem to be ESP on occasion—just by chance.
