Extrasensory perception, or ESP, refers to the apparent ability of a human being to "acquire information without using the [five] ordinary senses of the body and without depending on logical inference." ² Telepathy, clairvoyance, and precognition are all subdivisions of the broader ESP category. The term was made popular by J.B. Rhine in an attempt to separate the phenomena it describes from the mysticism of spiritualism and instead link it with current scientific concepts.

In regards to mysticism, ESP is commonly referred to as the sixth sense,and can provide an individual with information about the past, present, and future. To some, such information is regarded as having originated in a second, or alternate, reality.

In the laboratory, many parapsychologists prefer to use the term general ESP (or GESP) to avoid having to label a particular experimental result as being caused by telepathy or clairvoyance, since it cannot be stated for certain which of the two caused the result. For example, in many remote-viewing experiments designed to test clairvoyance, it may be that the subject is obtaining the information from the mind of the traveler (telepathically). Or in other tests, such as the ganzfeld, in which a person tries to send an image to another person, it may be that the receiver is using clairvoyance to view the image.

In general, the reported spontaneous cases of ESP amongst the public typically consist of information related through dreams (the most common), waking impressions, or sensory hallucinations (the least common).

Psychic dreams typically come in two forms: realistic and unrealistic. The most common type of psychic dream is the realistic dream, in which one dreams of something that is currently happening or about to happen. These dreams are often extremely detailed and appear as if the dreamer were watching the events unfold from a particular vantage point.

The unrealistic, or symbolic, dream conveys information in symbolic terms or in outright fantasy. While the occurrences in the dream may bear little resemblance to an actual event, the message is conveyed nonetheless. Since ordinary dreams are often unrealistic, it is not surprising that psychic dreams will also appear as such. Psychic symbolic dreams are typically set apart from common dreams by the fact that they often carry a certain sense of importance to the dreamer.

In many cases observed by Dr. Louisa E. Rhine, it was found that realistic and unrealistic elements were rarely mixed in a psychic dream. However, the reason for this, or why some people have realistic dreams and others symbolic, is not known. Part of the answer may be found in the individual's "psychological makeup and predispositions to certain types of dreaming." ²

Waking impressions can be defined as intuitions or sudden hunches, ideas, or insights that seem to arrive without any deliberate effort or forethought. "Like dreams, the bulk of waking impressions are the result of ordinary psychological processes at the unconscious level...the unconscious fitting together of little bits of information from many sources, resulting in a sudden click and a leap into consciousness of the insight or intuition." ² For example, say one day person A is going about his business and briefly thinks that person B will call him today. Low and behold, the phone rings and person B identifies himself. While at a glance it seems that person A had some type of premonition, it may be that person B is overdue for a phone call, and both person A and person B unconsciously recognized this fact, resulting in person A thinking of person B and person B calling.

However, there are also types of apparent psychic experiences that resemble intuition but are very hard to explain on the basis of unconscious processes. By nature, intuitions involve little or no imagery, so they cannot be classified as realistic or unrealistic. The experient just knows something, and often that knowledge comes with an unexpected degree of conviction.

Take for example the situation described in one of the many letters detailing cases of spontaneous ESP written to the Institute for Parapsychology and examined by Louisa Rhine. In this letter, a man wrote about his divorced parents. He stated that would keep in touch with both of them through detailed letters, but they never kept in touch with each other. Then one day, while sitting and talking with his mother in Iowa, he noticed that her face took on a sudden expression of "astonishment--possibly agony." She proclaimed that his father was getting married. At first, he thought it was impossible because he had just gotten a letter from his father a few days ago, and the letter mentioned nothing of a marriage. However, soon after his meeting with his mother, he received a letter from his father telling him that he got married in New York, and to the son's astonishment, on the same day he had visited his mother. ²

Hallucinations, which are the least common type of spontaneous ESP, may or may not be realistic. Basically, hallucinations fall between the direct knowledge of intuitions and the pictorial knowledge in dreams. Like intuitions, they occur when one is awake, but like dreams, the information is inferred from sensory input. Hallucinations of a psychic nature can occur in circumstances that might trigger ordinary hallucinations, such as extreme stress or fatigue, but can also occur when there seems to be no particular cause. The distinguishing feature of psychic hallucination is that the information conveyed could not have come from "past memories or present inferences" (as it is believed that typical hallucinations are based on memories and other unconscious material). ²

The most common type of a hallucinated psychic experience is the crisis apparition, which includes seeing a person who is at that time experiencing a crisis or some type of trauma or injury, or is near death or at the moment of death. The Society for Psychical Research (SPR), which has conducted several field investigations of psychic phenomena since its founding in the late 1800's, proposed the theory that crisis apparitions are hallucinations by the percipient brought on by some sort of telepathic message from the person in the crisis.

Other types of psychic hallucinations include auditory hallucinations, such as hearing one's name being called, and hallucinated pain, such as sensing the pain of a loved one at the moment of crisis.

While many reported cases of spontaneous ESP do convey important information, such as that presented during crisis apparitions, many psychic experiences reveal only trivial information, for example, dreaming of viewing a certain location and traveling there the next morning

Another interesting fact arose from a meta-analysis of reported spontaneous ESP cases conducted by psi researcher Robert Van de Castle. This analysis revealed that in nearly half of the cases, "telepathic dreams involved family members, death was the predominant theme...and women were receivers twice as often as men, whereas [men were senders] in 60% of the cases." ⁶

Other meta-analyses also confirm that the majority of psychic experiences come in the form of dreams, and the majority of these dreams are precognitive, meaning that they convey information about an event not yet taken place. (Many parapsychologists have conjectured that ESP is facilitated in the dream state, possibly because the barriers surrounding the conscious mind appear to be thinnest during such altered states of consciousness.)

Such experiences, however, raise some difficult questions for parapsychologists, for example, "Can we use the information acquired through psychic experiences to change the future...or prevent a foreseen tragedy?" Other questions ask, "If the experience in [genuinely] paranormal, is it revealing what will inevitably happen, or is it warning what might happen if steps are not taken to avoid it?" ²

There are no answers to these questions. In some cases people have tried and failed to prevent some kind of tragedy, and in others, they have succeeded. The majority, however, do not try at all for fear of ridicule.

Moving away from the subject of spontaneous ESP, let us now briefly examine some attempts to bring ESP into the laboratory.

The foundations for parapsychology as an experimental science were established in the 1930's by Dr. J.B. Rhine at the Duke University Parapsychology Laboratory in Durham, North Carolina. Beginning with his famous deck of ESP cards, Rhine attempted to observe and measure ESP in the laboratory. Many variations of Rhine's original ESP-card guessing experiment have been created and tested throughout the years, but perhaps one of the most significant results came from a series of experiments known as the Pearce-Pratt experiments.

This series of experiments took place on Duke University's West Campus under the direction of J.B. Rhine. J. Gaither Pratt, the agent, was located in what was then the Physics Building. Once a minute he picked up a card from a well shuffled deck and, without looking at it, moved the card face-down onto a book. At that very minute, Hubert Pearce, who was located in a library one hundred yards away and who had a synchronized watch, tried to perceive the card on the book. Without meeting, both men deposited sealed records with Rhine--Pratt of the targets (which he recorded after the run) and Pearce of his calls--and then met to check the results.

Ultimately, four separate experiments were done with a total of 558 hits out of 1,850 trials (where 370 would be expected by chance). The odds against chance for these results were astounding: 22 billion-to-one. One implication of this experiment is that psychic ability is not limited by distance. (Other experimental results also seem to suggest that ESP is independent of such factors as geography, time, intelligence, age, or education.)

Early experiments such as these contributed greatly to establishing the existence of psi phenomena, however, such card guessing (and other forced-choice methods) have generally gone out-of-use in parapsychology experiments. (More recently, free-response type experiments, such as the ganzfeld, have become more common.) Of the remaining forced-choice style experiments, the vast majority involve the use of technology, ensuring such controls as randomness and the elimination of human recording errors.

One popular use of technology is in the form of computer games, which help in keeping a subject's interest. Indeed, it has been shown in several experiments that an integral part of achieving successful results rests on the interest and morale of the subject.

One of the most important tasks facing a parapsychologist in the laboratory is determining how to facilitate the production of psychic phenomena in a controlled laboratory setting. While such phenomena often appear sporadically in daily life, parapsychologists cannot sit around waiting for a sudden, spontaneous burst of ESP ability. They must ensure that such abilities are present during the entire experimental procedure.

What some parapsychologists have discovered is necessary to facilitate the production of ESP in the laboratory is: a positive and warm subject-experimenter relationship, a sense of enthusiasm and confidence, feedback about one's psi performance, a non-analytic, intuitive, right-brain mode of functioning (i.e. trying to pay attention to images, feelings, and emotions), a feeling of relatedness with the world, a good dose of relaxation, a reduction of sensory input, and a shifting of awareness toward internal processes. ⁶

Yet another discovery that researchers have found (though this has always been known by mystics and yogis) is that in an altered state of consciousness, such as during REM sleep, a trance state, or in meditation, ESP abilities seem to be enhanced.

What many Eastern religions such as Hinduism have often taught is that meditation frees a person from outside distractions, allowing him to focus inwardly. What many ancient yogis discovered while meditating, though, is that this state is accompanied by the emergence of various paranormal powers. Once the consciousness has been freed from the signals of the external world, feelings of "clairvoyant omniscience" ² arise and may be accompanied by such physical effects as those experienced later by the Catholic saints: levitation and object movements.

One theory regarding the apparent facilitation of ESP during times of altered states of consciousness is that during these times, the mind is unable to filter out information that it thinks is irrelevant into the subconscious, thereby allowing for the full perception of all surrounding information.

This coincides with the possibility that there is a large difference "between the reception of psi information [and] its conscious detection -- its manifestation in the person's conscious mind." ⁶ It may be that psi information is continually received at an unconscious level, but only surfaces into the conscious mind during an altered state of consciousness.

Despite the many findings that seem to facilitate ESP in the laboratory, there occurs a curious phenomena termed missing-ESP (also called reverse-ESP). Basically, it occurs among subjects who dislike ESP. Even though they are consciously trying to achieve good scores, they typically score lower than chance would predict. It is almost as if, as a result of their disbelief in ESP, they are "unconsciously sabotaging their own results." ⁶

A 1942 investigation run by Gertrude Schmeidler, a professor of psychology at City University of New York, tested the theory that those who did not believe in ESP scored below-chance results. In this investigation, Schmeidler created a questionnaire to explore students' beliefs about psi.

"She used the term sheep to refer to those who were confident about the reality of psi and goats for those who doubted its existence or its pertinence in the context of the test." After filling out the questionnaire, Schmeidler "gave the students a classic psi test with ESP cards in which they tried to guess sequences of target-cards. [She then] compared the results of the psi test [to] those of the questionnaire. The remarkable conclusion was that the 'sheep' had a significant deviation above chance, while 'goats' were significantly below it." ⁶

This effect, which has been termed the sheep-goat effect and has been confirmed by many independent researchers, demonstrates that "one's attitudes toward psi affects the likelihood that such phenomena will occur in the first place. The more an individual harbors a reductionistic view of the world, the less chance such phenomena will emerge (let alone be witnessed by them); the more one is interested in interconnectedness, and open to psi experiences, the more likely the world will respond by creating such experiences." ⁶

This now leads us to the question of how such experiences are created in the first place. Many theories regarding ESP have been formulated over the years, and while the majority have been dismissed by serious researchers (such as the idea that ESP is communicated through a form of radio waves), a few continue to be entertained.

One theory was presented by the famous novelist and muckraker Upton Sinclair, who reportedly had several psychic experiences of his own. Indeed, his wife, Mary Craig Sinclair, was reputed to be a rather talented clairvoyant. When asked what such abilities mean to them, the Sinclairs replied that, "It seems to indicate a common substratum of mind, underlying our individual minds, and which we can learn to tap. We are apparently getting hints of a cosmic consciousness, or cosmic unconsciousness: some kind of mind stuff which is common to us all, and which we can bring into our individual consciousness. Why is it not sensible to think that there may be a universal mind-stuff, just as there is a universal body-stuff, of which we are made, and to which we return?" ⁵

This statement closely resembles psychologist Carl Jung's theory of a collective unconscious into which the conscious mind has subliminal psychic access. During his studies, Jung noticed that certain symbols (such as age for wisdom or serpents for evil) were interpreted similarly by people of different backgrounds, and were included in the myths and legends of various different cultures. "The universality of [such] symbols led Jung to hypothesize a reservoir of mind matter...that exists...in some sort of continuum beyond the confines of time and space--[into] which the unconscious mind is able to tap." ⁵ This "collective racial unconscious" has also been interpreted as being something along the lines of an "inherited memory" of our sepcies' past, ³ or a vast repository of the accumulated wisdom and experiences of the human race.

Even Lousia Rhine once proposed the theory that ESP starts in the unconscious, which is a storehouse of memories, hopes and fears. At some point, contact is made between the objective world and the subconscious mind. However, an individual will remain unaware of this contact until the information is brought to the conscious level.

A physics twist to this theory of a collective unconscious involves the supposed existence of a dimension which contains information perceivable through psi. Many physicists and mathematicians already claim that a fourth dimension (aside from width, height, and depth) exists, though it is not visible to the human eye. Many also speculate that as many as eleven to twenty-six other dimensions exist, and that at least one of these is somehow related to the mind, allowing the mind to tap into it and retrieve information. However, there is no definite evidence to support these theories. ⁵

Another theory attempting to explain ESP involves macrophages, which are cells present in connective tissue, lymph nodes, and bone marrow, and which are tied to nerve endings. It is thought these might be the body's ESP organs, sending and receiving impressions below the normal perceptive level.

Other theories involve the possibility of the existence of two realities: a physical and an astral. It is believed that ESP occurs when there is an integration between both realities, perhaps caused by a leak in the barriers separating both realities. However, this would occur infrequently, else all unconscious thought flood and overflow the conscious mind, a condition which the mind could not withstand.

Some theories do not concern how ESP is caused, but rather which individuals possess ESP and how they acquired this ability.

One theory holds that some people such as seers, prophets and diviners were born with the gift, and that such talents are inherited. Another theory holds that it is a primordial sense which has decreased in populations as cultures have advanced. Still another theory claims ESP is a supersense which evolves in the nervous system.

Again, it must be reiterated that there remains to be seen any concrete proof that any one theory is more likely than another. It may be that none of the preceding theories are correct. Only time, and the continuation of research into such areas, will tell.