How ESP Works

Extra­sensory perception is a collective term for various hypothetical mental abilities. These abilities (along with other paranormal phenomena) are also referred to as psi.

The major types of ESP are:

A closely related psi phenomenon, not technically part of ESP, is telekinesis, the ability to alter the physical world with mind power alone.

­All of these abilities are based on the idea that human beings can perceive things beyond the scope of known bodily senses. This concept has been around since the beginning of human civilization, under many different names, but the modern conception didn't develop until the­ first half of the 20th century. The term ESP itself was coined in 1934, by Duke University professor J.B. Rhine, one of the first respected scientists to conduct paranormal research in a university laboratory.

ESP believers around the world have different ideas of how these abilities manifest themselves. Some people believe everybody possesses these abilities, and we involuntarily experience moments of ESP all the time. Others say only a handful of psychics, shamans or mediums have the special power, and that they can only access this power when they put themselves into a special mental state. Most believers think that everybody has the potential for ESP, but that some people are more in tune with their paranormal abilities than others.

Believers also disagree­ on how ESP actually works. One theory says that, like our ordinary senses, ESP is energy moving from one point to another point. Typically, proponents of this theory say ESP energy takes the form of electromagnetic waves -- just like light, radio and X-ray energy -- that we haven't been able to detect scientifically.

This theory was fairly popular in the early 20th century, but it's out of favor today due to several inherent problems. For one thing, the explanation only accounts for telepathy, not clairvoyance or precognition. Presumably, if the information travels as electromagnetic energy, it has to be sent by someone -- it has to travel from mind to mind. It doesn't explain how information would move through time or from an object to a mind.

Secondly, the theory doesn't jibe with what we know about ourselves and the universe. In most reported cases of telepathy, ESP works totally independent of distance. That is, the power of the "signal" is the same whether the transmitting mind and the receiving mind are in the same room or on opposite sides of the earth. No other form of energy behaves this way, skeptics point out, so it doesn't make sense that "psi waves" would either. Furthermore, it seems strange that we haven't found any unexplained sense organs in the body that might pick up on this energy, nor any evidence of the energy waves themselves.

In light of these problems, the prevailing theory among believers today is that ESP is a result of something beyond the known physical world. For example, many people view it as "spillover" from another reality. According to this theory, in addition to the physical universe we are consciously aware of, we all exist in another dimension that has completely different governing laws. Time and space work very differently in the other reality, allowing us to know about other people's thoughts, distant events or things that haven't happened yet in the physical reality. Normally, our awareness of this plane of existence is completely unconscious, but every once in a while, the conscious mind picks up on this information.

Needless to say, this theory is also completely outside our scientific understanding of the world. But, according to the theory's proponents, it's not supposed to fit into that conception. Like the concepts of God or an afterlife, the hypothetical reality would not rely on the physical laws of the universe. It would depend on the existence of a soul of some sort.

Most believers come by their convictions either through personal experience or anecdotal evidence. If you have a dream that eventually comes true, in strikingly similar detail, you might very well take it as proof that you're psychic. And if you hear enough incredible ESP stories from reliable sources, you may have a harder and harder time discounting the phenomenon.

Undeniably, the world is full of both of these forms of evidence. Most of us encounter extraordinary coincidences now and then, and there are many well-documented cases of apparent precognition and clairvoyance. For example, in 1898, Morgan Robertson published "Futility," a novel about a huge luxury liner called the Titan. The story allegedly came to him in a sort of trance. In the novel, the ship zips through dense fog late one April night, crashes into an iceberg and sinks, killing hundreds of people. Fourteen years later, the Titanic, similar in size and structure to the fictional ship, did exactly this, at the same time of year, under the same conditions. For both the fictional ship and the real ship, the casualties were high because there weren't nearly enough lifeboats on board.

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­­There are dozens of other famous stories, most not as well documented, de­ta­iling major and minor examples of apparent ESP all over the world. But as compelling as these stories may be to believers, they're of limited use to scientists because they occur in an uncontrolled environment. In order to effectively demonstrate something with hard evidence, scientists need to conduct structured laboratory experiments with closely controlled conditions.

Since the 1930s, parapsychologists around the world have been doing just that. J.B. Rhine, often dubbed the father of parapsychology, was behind one of the earliest and most famous efforts, the Zener cards experiments. The original Zener cards (named after their designer, Karl Zener) were a deck of 25 plain white cards, each printed with one of five simple, distinct patterns. Each deck contained five cards of each pattern, so anybody had a one-in-five chance of correctly guessing the pattern on any particular card.

The experiment was simple: Rhine would ask his subject to guess which pattern was on each card and record the result. On average, random guessing would yield five "hits" (correct guesses) per deck of 25. Rhine reasoned that consistent accuracy above that level, barring any cheating, indicated ESP ability.

The scientific community was certainly surprised, and largely incredulous, when Rhine claimed in his treatise, "Extra-Sensory Perception," that some of his subjects consistently guessed correctly above chance levels. Many disputed Rhine's methods and his credibility, but in general, he was regarded as a legitimate, sincere scientist.

In the years since Rhine's pioneering work, hundreds of parapsychologists have conducted similar experiments, sometimes with the same positive results. Most of these researchers have moved away from the rigid patterns of Zener cards to more open-ended images, such as paintings or photographs. In a typical experiment, a "sender" will concentrate on a particular image (a target) and try to communicate it telepathically to an isolated subject. The "receiver" subject describes what he sees in his mind, and the research team records his impressions. At the end of the session, the receiver attempts to pick the correct target out of a collection of images created from his impressions during the session.

In ganzfeld (German for "whole field") target experiments, developed in the 1970s, the receiver is deprived of sensory information to make it easier to focus on ESP messages. The subject lies in a room filled with dim red light, listening to white noise, with his or her eyes covered (by halved Ping-Pong balls in the conventional experiment). Most of the time, receivers in these experiments are way off in their guesses, but some subjects do describe the target images in striking detail. There are several examples of impressive hits at PSI Explorer: The Ganzfeld Experiment. In similar experiments, designed to test clairvoyance alone and not telepathy, there is no sender, only a receiver.

In ­another popular experiment, subjects attempt to influence a machine, such as a random number generator, with their minds. Over the course of hundreds of runs, researchers have found that subjects do appear to have some influence over machine behavior, though it is very slight. Check out Princeton's Engineering Anomalies Research department Web site for more information.

­Parapsychology has gained a lot of credibility over the past 100 years, but there is s­till a strong contingent of skeptics who see ESP studies as misguided at best and completely worthless pseudoscience at worst.

For a number of these skeptics, the primary argument against ESP is, quite simply, that it doesn't make any sense. As we saw earlier, the existence of the ESP phenomenon is fundamentally at odds with the known "rules" of the universe, as supported by countless scientific experiments. As much as we might want to believe it, these skeptics say, ESP is just too extraordinary to accept without equally extraordinary evidence.

And the widespread anecdotal evidence of ESP, they say, certainly isn't extraordinary -- not when you consider the big picture. To the average person, a dre­am or feeling coming true, in precise detail, seems too amazing to be simple coincidence. But if you look at it from a statistician's viewpoint, it's much less incredible. There are more than 6 billion people on Earth, constantly thinking and all experiencing dozens of significant events every day. Statistically, on any particular day, some of the things some people envision will line up closely with some of the things those people happen to experience. In all of your time on Earth, this will undoubtedly happen to you now and then. Add to this the desire for an afterlife, the skeptics say, and it's no wonder such a large section of the population deludes itself into believing in psi phenomenon.

The chances of a hit climb even higher when you consider people's ability to make reasoned, educated guesses. For example, Morgan Robertson's apparent prediction of the Titanic disaster seems less incredible when you learn that he was a former seaman who knew a lot about modern ship technology. His book correctly guessed details of the real ship and the crash, skeptics say, because he had a good understanding of how a ship like that would be built, how it might get into trouble and what would happen in that scenario.

Similarly, some people may seem to have psychic powers when they really just have heightened intuition. Your five senses are constantly picking up on information, and your brain is constantly processing this information on an unconscious level. Some people are particularly adept at analyzing seemingly irrelevant information and putting the pieces together to make highly accurate guesses. For example, you might inexplicably know when somebody is lying to you because you unconsciously recognize subtle variations in facial expression or tone of voice.

Many ESP believers counter these arguments with the assertion that true psychic visions aren't everyday thoughts, but rare revelations easily distinguished from a person's normal thinking. If you only consider these special visions, they argue, the coincidence explanation doesn't hold up. The educated guessing theory may explain a lot of apparent revelations, they say, but not all.

In any case, it's clear that human nature does lead people to focus on a few instances of extraordinary coincidence as evidence of something supernatural, while completely ignoring the thousands of dreams and visions that don't line up with reality in any remarkable way. Out of context, the individual hits are very impressive, especially if you start to misremember your thoughts so that they correspond even more closely with reality. Whether or not this accounts for all alleged ESP phenomena, it most likely accounts for a lot of it.

­It's not too difficult to explain anecdotal evidence of ESP, but scientific data is a little trickier. The common skeptical view is that parapsychologists' positive lab results come from problems with the experiment or plain old bad science. If the researcher's mathematical model is faulty, for example, simple chance guessing might look like something exceptional. Or the researchers could accidentally influence the subject to pick the right target. This could certainly happen, if the experiment isn't tightly controlled. In Rhine's early experiments, for example, he knew the correct card and he usually made eye contact with the guesser. The subject could have guessed correctly by unconsciously picking up on Rhine's body language -- what looked like ESP could have been simple intuition. Rhine later im­proved his methods, and his subject's accuracy did drop off somewhat.

The biggest problem with a lot of ESP research is it isn't reproducible. That is, one scientist may get results that another scientist can't get by replicating the experiment with different subjects. Parapsychologists might point out that some people aren't as psychically in-tune as others, so different subjects will yield different results, but the stigma still sticks. Reproducible results are essential to the conventional scientific method, so many scientists discount any irreproducible data no matter how credible the source.

In some cases, skeptics charge that ESP evidence is the product of outright fraud. There have certainly been experiments where parapsychologists manipulated data to support their own theories (this has occurred in most, if not all, scientific disciplines), and even an innocent scientist can have a hard time disproving these claims. Accusing a respected scientist of fraud is pretty serious business, however, so most skeptics are hesitant to take that step.

Skeptics are much more likely to point out fraud in unscientific ESP demonstrations, such as stage psychic shows. Most parapsychologists are also wary of ESP demonstrations for entertainment, simply because it's too easy to create the illusion of psychic powers.

The most ubiquitous fraudulent method is cold reading, in which the stage psychic rapidly throws out general, broad suggestions to an audience member until something "hits." For example, the psychic might say, "I see a man very close to you -- the name starts with J -- Jason, John, Jim? -- An uncle, or grandfather, or older friend?" Objectively, you can see that this is so broad it could apply in some way to just about everybody. But in the moment, subjects typically concentrate on any correct guesses and ignore everything that misses. It's the age-old trick of never being wrong and occasionally being right.

Most parapsychologists recognize that the skeptical viewpoint is largely beneficial to the public's understanding of ESP phenomena. High-profile skeptics, such as former magician James Randi, help steer the ESP discussion away from emotional responses and toward logical analysis by unmasking f­alse psychics and providing other reasonable explanations for apparent paranormal phenomena. By explaining the statistics of coincidence and the tricks of the magic trade, these skeptics get the public thinking critically about its beliefs and assumptions.

But skeptics like Randi can also detract from the ESP discussion. Randi is widely known for his offer of one million dollars to anyone who can prove the existence of paranormal phenomena in a supervised demonstration. So far, nobody has been able to claim the prize, which Randi suggests is evidence that none of this stuff exists. Several high-profile professed psychics have accepted the challenge and then backed out, which certainly casts them in a bad light.

To many parapsychologists and ESP believers, Randi's challenge is just theatrics, like the psychic stage shows he exposes. Generally, legitimate scientists are not in the business of claiming prize money in publicized demonstrations, nor are they necessarily out to prove ESP's existence in the first place. The primary mission of science is to investigate truth -- generally speaking, scientists are not out to profess their own beliefs, only their own findings. By lumping legitimate researchers in with entertainers, skeptics may confuse the issue.

ESP believers mainly find fault with the implication that providing a logical explanation for apparent psychic phenomena and unmasking false psychics disproves the existence of ESP. It's an absolute certainty that many demonstrations of psychic power are fraudulent; it's also certain that experiments will be imperfect, and that data may turn out to be useless. But this has no bearing on the validity of the theory itself.

When all is said and done, we simply don't know whether ESP exists. Given what we do understand about the way physics operates in the universe, ESP doesn't make any sense, but this is not a valid reason to rule it out. In the history of mankind, thinkers have reevaluated their model of the universe many times in response to new evidence. The scientific process is never about deciding what can't be; it's always about figuring out what is.