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precognition or second sight

“To the present day, no one has come up with a persuasive experimental design that can unambiguously distinguish between telepathy and clairvoyance....Based on the experimental evidence, it is by no means clear that pure telepathy exists per se, nor is it certain that real-time clairvoyance exists." The evidence "can all be accommodated by various forms of precognition."--Dean Radin

"Statistical significance can be totally meaningless and it usually is."-- James Alcock

Precognition is psychic knowledge of something in advance of its occurrence. The faculty of seeing into the future is called "second sight" if it is not induced by scrying, drugs, trance, or other artificial means.

Since there is no way to distinguish direct communication with another mind from communication with a past or future perception by that or some other mind, there is no way to distinguish telepathy from precognition. There is no way to distinguish telepathy, clairvoyance, retrocognition, or precognition from a mind perceiving directly the akashic record. There is no way to distinguish telepathy, clairvoyance, retrocognition, precognition, or perceiving the akashic record from perceiving what is directly placed in the mind by a god (occasionalism). There is no way to distinguish telepathy, clairvoyance, retrocognition, precognition, perceiving the akashic record, or having perceptions directly implanted in our minds by some god from perceiving the hidden record of all perceptions in the eleventh dimension that is vibrating in the intersection between the tenth and twelfth dimensions. I could go on, but it would be too annoying.

People can predict the future. We do it all the time, but we usually, if not always, do it by taking into account our experience, knowledge, and surroundings. Some predictions by psychics come true. So do some predictions by non-psychics. No doubt much of our anticipation of the future is unconscious and second nature, but it is based on quite natural and mundane abilities, not on mysterious or supernatural powers.

If a person could provide accurate and detailed descriptions of future events on a regular basis, that person would be celebrated as truly psychic. That no such person has ever existed in recorded history is a sign that stories of people with second sight are mythical exaggerations.

In 1994, biologist Rupert Sheldrake published a report on a psychic dog, Jaytee, a terrier who has precognition (Dogs That Know When Their Owners Are Coming Home: And Other Unexplained Powers of Animals). In 1998, psychologists Richard Wiseman and Matthew Smith tried to replicate the Jaytee experiment and failed. (The belief in psychic dogs seems to be popular among true believers in the paranormal.)


One of the latest attempts at establishing the reality of precognition in a scientific experiment involves measuring galvanic skin response or brain activity (as measure by an fMRI) in presentiment experiments. Presentiment is a feeling that something strange or unusual is about to happen. If the feeling is especially foreboding, it is called a premonition. In presentiment experiments, however, what is measured is not the conscious feeling of anything, but the alleged unconscious effect on a machine of a physical response occurring before a stimulus is presented. Those doing this kind of research have no way of knowing that what they observe on their machines is in any way related to the stimuli they present. Assuming such a connection begs the question. The researchers might equally assume that the electrical resistance of skin in a subject or the blip of color on an fMRI caused the researcher to select the stimulus presented.

In 1993, Dean Radin got the idea "to monitor a person's skin conductance before, during, and after viewing emotional and calm pictures, and then see if the autonomic nervous system responded appropriately before the picture appeared" (2006, p. 184). He eventually did four tests with mixed results, but a meta-analysis saved the day. The first test was small (24 subjects) and he found that the subjects reacted 2 to 3 seconds after the presentation of the stimulus, as measured by a blip on a screen hooked up to a skin conductance measuring device. He also found blips occurring before the stimulus and he calculated their odds against chance at being 500 to 1, for what it's worth.

His second experiment had 50 subjects. All he says about it is that the "results were in the predicted direction, but weren't as strong as those observed in the first experiment." The third experiment had 47 subjects. He says it "resulted in a strong presentiment effect, with odds against chance of 2,500 to 1." The third experiment used different hardware, software, and pictures. The fourth study produced results that "weren't statistically significant."

Radin concludes:

These studies suggest that when the average person is about to see an emotional picture, he or she will respond before that picture appears (under double-blind conditions). (2006, p. 188, emphasis in the original)

That's how Radin sees his work. I see a mixed bag of results that assumes blips on a screen are caused by psychic means. The studies may be double-blind, but they don't use meaningful controls. Radin's kicker, however, is his meta-analysis. He lumped together the data from the four studies and produced a paper published in The Journal of Scientific Exploration (2004) called "Electrodermal Presentiments of Future Emotions." Voila! The odds against chance of getting just the results he got? 125,000 to 1, he says (2006, p. 188).

He concludes his defense of the evidence for presentiment with mention of several "replications," one of which involved testing earthworms. In the earthworm experiment, Radin says that the "results were very nearly statistically significant" (2006, p. 171). How comforting. Other "replications" involved using machines that measure heart rate and electrical activity in the brain, as well as skin conductance. All assumed that the various blips they produced were caused by paranormal phenomena.

"Based on the experimental evidence, it is by no means clear that pure telepathy exists per se, nor is it certain that real-time clairvoyance exists," says Radin. The evidence, he says, "can all be accommodated by various forms of precognition."

scientific evidence for precognition

The strongest evidence for precognition, according to Radin is a meta-analysis of all published reports in English of “forced-choice” experiments on precognition conducted between 1935 and 1987 done by Charles Honorton and Diane Ferrari (1997, p. 113). They found 309 studies in 113 articles by 62 investigators: nearly 2 million trials involving more than 50,000 subjects. There was very little uniformity in these tests. They involved different kinds of guesses (ESP cards, die face, symbols, etc.), different methods of randomization, different size samples, different time intervals between guessing and unveiling, etc. Only 23 of the 62 investigators (37%) got positive results. He doesn’t tell us what percentage of the studies got positive results. Yet, Radin proudly proclaims that the odds against chance of the results were on the order of 1025 to one. “This eliminated chance as a viable explanation,” he says (p. 114). Yes, it certainly does! He also eliminates the file-drawer problem as an explanation because he used some sort of statistical formula (not revealed here) to arrive at 14,268 as the number of papers that would have to be in the drawer to tip these odds back to chance. Radin concludes from this that “the precognition effect had been successfully replicated across many different experimenters.”

Radin notes that Honorton and Ferrari dumped the outliers, the top and bottom 10% (highest and lowest results). They then produced odds against chance of a billion to one. Radin calls this “effectively the same” as the result for all the studies. I don’t think ten million billion billion to one is “effectively the same” as a billion to one, except in the sense that they're both absurd.  

When the quality of the studies was evaluated, there was no difference in outcome between the well designed and the poorly designed studies (though the quality of the studies improved over time). Radin thinks this is because the precognitive effect was “remarkably stable” (p. 115).  He says Honorton & Ferrari identified eight elements of good experiments for precognition studies, but he only mentions four: 1) specifying how many samples would be collected; 2) planning the method of statistical analysis; 3) using proper randomization methods; and 4) using automated recording. In analyzing variables, they found that 42.6% of the studies that provided trial-by-trial feedback were successful. According to Honorton and Ferrari: "Studies in which subjects are given trial-by-trial or run-score feedback have significantly larger effects than those with delayed or no subject feedback."*

Radin thinks that because certain predictions were made that seem to have been validated, it shows that “precognition performance was not merely a statistical oddity” because it seems to vary in ways that made sense “psychologically.” He thinks this suggests some sort of lawful relationship going on that can guide future research. Skeptics might be concerned that a closer look at the randomization techniques and feedback methods might reveal the basis for this apparent lawful relationship. In any case, the whole idea of concluding anything important based on a meta-analysis of this kind seems preposterous. Finally, as psychologist Jim Alcock (2003) has pointed out many times: these researchers don't give the null hypothesis a chance.

At times, Radin seems to lose touch with reality, as when he posits testing for “unconscious precognition” to investigate “the possibility that the mind is in contact with its own future state.” He suggests we test whether future perceptions interfere with present performance on reaction-time tasks, but he doesn’t tell us how he’d do this. He also suggests we test whether future emotional states are detectable in present nervous system activity (p. 116). Again, he gives no hints as to what he might be talking about. Even if we found, for example, that certain nervous system activity (such as the production of adrenalin) precedes the feeling of anxiety, that would have no bearing on the precognition issue. (Maybe Radin was having a presentiment of experiments on presentiment that he would do later! In Entangled Minds [pp.166-168] he reports on the four small experiments he did on presentiment that were mentioned above. He got mixed results, but when he did a meta-analysis, guess what? He found that his results showed odds of 125,000 to 1 against chance!

Daryl Bem in 2010: anomalous retroactive influence

Psi researcher Daryl Bem (he of Bem and Honorton fame) has had a paper on precognition accepted by a peer-reviewed publication of the American Psychological Association: the Journal of Personality and Social Psychology. He's titled his paper "Feeling the Future: Experimental evidence for anomalous retroactive influences on cognition and affect."  Anomalous retroactive influence is psiency talk for precognition and presentiment. (Psiency is snarky talk for psi jargon.)  He modified a standard test of priming. Instead of showing subjects a word like ugly or beautiful before they viewed a picture of something like a lovely sunset or a couple making love and then testing how long it takes to respond either favorably or unfavorably to the picture, Bem showed the picture first, measured response time, and then showed the "priming" word. (You must give the guy credit for coming up with this concept.) His method is to do just the right number of tests that will provide him with a large enough sample to ward off criticism that his sample was too small and that also provides data that deviate from chance expectation with "statistical significance." His hypothesis will be that if he can show that his subjects as a group showed response times predicted by priming experiments that statistically are unlikely to be due to chance, then he has shown that precognition is occurring. Other experiments involved things like testing "recall," except the students were asked to "recall" words before rehearsing them, or asking for preference between an emotively neutral picture and its mirror image before the target is selected by the computer. (Describing each experiment would be tedious. The reader is directed here.) Of course, Bem doesn't put it quite like I have. Here's what he writes on his website:

The term psi denotes anomalous processes of information or energy transfer that are currently unexplained in terms of known physical or biological mechanisms. [RTC comments: This is not true. The term psi denotes not a process of information or energy transfer, but a statistic. Psi researchers assume that this statistic represents a real transfer of information. This is the psi assumption that Bem and many others in the field make. So, those headlines that read "Study finds evidence of precognition" are misleading. The study found a statistic that the researcher assumes is due to precognition. But who would read a press release or a story with that headline?]

Two variants of psi are precognition (conscious cognitive awareness) and premonition (affective apprehension) of a future event that could not otherwise be anticipated through any known inferential process. Precognition and premonition are themselves special cases of a more general phenomenon: the anomalous retroactive influence of some future event on an individual’s current responses, whether those responses are conscious or nonconscious, cognitive or affective.

This article reports 9 experiments, involving more than 1,000 participants, that test for retroactive influence by “time-reversing” well-established psychological effects so that the individual’s responses are obtained before the putatively causal stimulus events occur.

Data are presented for 4 time-reversed effects: precognitive approach to erotic stimuli and precognitive avoidance of negative stimuli; retroactive priming; retroactive habituation; and retroactive facilitation of recall. [Did I forget to mention that this experiment allows you to show college kids "erotic stimuli" or pornography, dirty pictures, or smut as some might call it?]

The mean effect size (d) in psi performance across all 9 experiments was .21, and all but one of them yielded statistically significant results. The individual-difference variable of stimulus seeking, a component of extraversion, was significantly correlated with psi performance in 5 of the experiments, with participants who scored above the midpoint on a scale of stimulus seeking achieving a mean effect size of .42.

Skepticism about psi, issues of replication, and theories of psi are also discussed.

There remains no plausible mechanism by which precognition (or any other psychic phenomenon, for that matter) could work. Some researchers have hung their speculative hopes on baffling applications of quantum mechanics. Some still find anecdotes the most powerful evidence. Most, however, are banking on occult statistics to baffle peer reviewers, the media, and the general public.

[new] University of Edinburgh psychologist Stuart Ritchie, University of Hertfordshire psychologist Richard Wiseman, and University of London psychologist Christopher French each replicated the Bem experiment at their respective universities with 50 participants each. And each found no evidence of precognition or any other psychic ability. They also found that no journal wanted to publish their negative results, not even the Journal of Personality and Social Psychology, the journal of the APA that published Bem's study. [For more on the story about the failed replication and the difficulty these researchers have had getting their work published see here, here and here.][/new]

Skepticism is minimal in the field of psi research, except for skepticism about consensus science in physics and biology. In his discussion of skepticism in a posted draft of his paper, Bem writes:

The major theoretical challenge for psi researchers is to provide an explanatory theory for the alleged phenomena that is compatible with physical and biological principles.

You can see the psi assumption at work in this assessment. The real challenge, as I see it, is to prove that these statistical deviations from chance are not due to statistical flukes; faulty equipment; fine equipment affected by temperature, humidity, altitude, electro-magnetic interference from nearby equipment or personal items carried by subjects or researchers, etc.; errors in data recording, collection, collating, and in calculations from the data. The only alternative hypotheses Bem considers are precognition, clairvoyance, psychokinesis, and an artifact of the random number generator (RNG). The tests are administered by computers that use an RNG to randomize items in the tests. Bem posits that it's possible that participants access "already-determined information in real time, information that is stored in the computer." Or, they might be "actually influencing the RNG’s placements of the targets." Finally, he considers that the output from the RNG might be "inadequately randomized, containing patterns that fortuitously match participants’ response biases. This produces a spurious correlation between the participant’s guesses and the computer’s placements of the target picture." Satisfied that he's adequately handled these other possibilities, Bem moves on.

There is also the problem of cheating and sloppiness. Zealous psi researchers, depending on very small deviations from chance (Bem's subjects scored 1.7 to 3 percent above chance overall) to get the statistic they want, can't be assumed to always be honest and careful in the running of their labs. History is against them. Still, they do provide some side-splitters along the way. Consider: Bem concluded from his experiments "that there's a slight but statistically significant precognition effect, particularly if the person making the prediction is a stimulus-seeking extrovert." (CosmicLog on MSNBC. For a skull-splitting hoot read the commentary from RevLucifer about precognition being explained by antimatter traveling backward in time.)

As Ernest Rutherford once said: “If your result needs a statistician then you should design a better experiment.”*

In addition to the researchers mentioned above who failed to replicate Bem's experiment, Jeff Galak of Carnegie Mellon University and Leif D. Nelson of University of California, Berkeley, also failed in their attempt at replicating one of Bem's nine experiments (number 8, the one involving "recall"). The conclusion stated in the abstract of this other study reads:

We replicated the procedure of Experiment 8 from Bem (2010), which had originally demonstrated retroactive facilitation of recall. We failed to replicate the result. The paper includes a description of our procedure and analysis as well as a brief discussion for some reasons why we obtained a different result than in the original paper.

Bem considers some of his experiments to be replications of others. Replication is important in scientific experiments, but the concept becomes ludicrous when applied to the kind of statistic-seeking research Bem and other psi researchers (e.g., Dean Radin) do. We already know that if you do enough experiments there is a high probability that you will find some that yield the statistic you seek. But nobody in his right mind will identify a statistically significant statistic with real evidence of precognition. To Bem, Radin, and other psi researchers, I say: Just find one person who can reliably pick the winner at the race track or the state lottery, or give us fair warning of the next terrorist attack, and all skeptics will bow at your feet.

Members of the American Psychological Association should be embarrassed that Bem's work is being published in one of their journals without requiring him to tone down his claims. He has not shown proof of any psychic power (as he and some commentators are claiming). He's found a slight deviation from chance in his data that is statistically significant. All that means is that the slight difference he found (somewhere between 1.7 and 3%) is not likely due to chance. He's assuming it is due to "anomalous retroactive influence." The reviewers should have required Bem to admit that he does not know why his data are what they are. At best, he is justified in claiming that one possibility is that some subjects some of the time were affected by something from the future. Given what we know about nature, that possibility is not in the least bit plausible. It is disheartening to see this study published in its current form in a respected journal and to read in a blog on Psychology Today that this is "cutting-edge science." (For more on the Bem paper see James Alcock Back from the Future: Parapsychology and the Bem Affair; Bem's response to Alcock and Alcock's response to Bem's response; Richard Wiseman Bem Replications; reader comments; Wagenmakers, Wetzels, Borsboom, and Maas Why Psychologists Must Change the Way They Analyze Their Data: The Case of Psi; Nicolas Gauvrit Precognition or Pathological Science?; and Gergö Hadlaczky Precognitive Habituation: An attempt to replicate previous results.)

See also clairvoyance, ESP, parapsychology, psi, psychokinesis, remote viewing, retrocognition, telepathy, part eight of my review of The Conscious Universe, and A Short History of Psi Research by Robert Todd Carroll.

reader comments on precognition

reader comments on psi in general

further reading

books and articles

Alcock, James E. (1981). Parapsychology: Science or Magic? Pergamon Press.

Alcock, James E. Science and Supernature: a Critical Appraisal of Parapsychology (Buffalo, N.Y.: Prometheus Books, 1990).

Alcock, James E. (1995) "The Belief Engine," Skeptical Inquirer. 19(3): 255-263.

Alcock, James. 2003. "Give the Null Hypothesis a Chance," in Psi Wars - Getting To Grips With the Paranormal. ed. James Alcock, Jean Burns and Anthony Freeman. Imprint Academic, pp. 29-50.

Bem, Daryl J. and Charles Honorton (1994). "Does Psi Exist?" Psychological Bulletin, Vol. 115, No. 1, 4-18.

Blackmore, S. J. (1980). "The extent of selective reporting of ESP ganzfeld studies," European Journal of Parapsychology 3:3 , 213–220.

Blackmore, Susan. (2001.) "What Can the Paranormal Teach Us About Consciousness?" Skeptical Inquirer, March/April.

Blackmore, Susan (2003). Consciousness: An Introduction. Oxford University Press.

Christopher, Milbourne. ESP, Seers & Psychics (Thomas Y. Crowell Co. 1970).

Christopher, Milbourne. (1975). Mediums, Mystics & the Occult. Thomas Y. Crowell Company.

Cole, Richard. "U.S. didn't foresee faults in psychic spies program," Associated Press, Sacramento Bee, Nov. 29, 1995, A2.

Frazier, Kendrick. editor, Science Confronts the Paranormal (Buffalo, N.Y.: Prometheus Books, 1986).

Frazier, Kendrick. editor. The Hundredth Monkey and Other Paradigms of the Paranormal, (Buffalo, N.Y.: Prometheus Books, 1991).

Gardner, Martin. Fads and Fallacies in the Name of Science (New York: Dover Publications, Inc., 1957).

Gardner, Martin. Science: Good, Bad and Bogus (Buffalo, N.Y.: Prometheus Books, 1981).

Gardner, Martin. How Not To Test a Psychic: Ten Years of Remarkable Experiments With Renowned Clairvoyant Pavel Stepanek (Buffalo, N.Y.: Prometheus Books, 1989).

Gardner, Martin. On the Wild Side (Amherst, N.Y.: Prometheus Books, 1992).

Gordon, Henry. Extrasensory Deception: ESP, Psychics, Shirley MacLaine, Ghosts, Ufos  (Buffalo, NY: Prometheus Books, 1987).

Hansel, C. E. M. The Search for Psychic Power: ESP and Parapsychology Revisited (Buffalo, N.Y.: Prometheus Books, 1989).

Hansen, George P. (2001). The Trickster and the Paranormal. Xlibris Corporation.

Hines, Terence. Pseudoscience and the Paranormal (Buffalo, NY: Prometheus Books, 2003).

Hyman, Ray. The Elusive Quarry : a Scientific Appraisal of Psychical Research (Buffalo, N.Y.: Prometheus Books, 1989).

Hyman, Ray. (1995). "Evaluation of Program on Anomalous Mental Phenomena," Journal of Scientific Exploration, Volume 10 Number 1.

Keene, M. Lamar. The Psychic Mafia (Prometheus, 1997).

Luckhurst, Roger. 2002. The Invention of Telepathy: 1870-1901. Oxford University Press.

Marks, David. The Psychology of the Psychic (Buffalo, N.Y.: Prometheus Books, 2000).

Milton, Julie and Richard Wiseman. (1997). Guidelines for Extrasensory Perception Research. University of Hertfordshire Press.

Neher, Andrew The Psychology of Transcendence (1980). This Prentice-Hall book is out of print. Used copies may be available from Amazon.com. It was reissued in 1990 by Dover Books as Paranormal and Transcendental Experience.

Radin, Dean (1997). The Conscious Universe - The Scientific Truth of Psychic Phenomena. HarperCollins.

Radin, Dean. (2006). Entangled Minds: Extrasensory Experiences in a Quantum Reality. Paraview Pocket Books.

Randi, James. Flim-Flam! Psychics, ESP, Unicorns, and Other Delusions (Buffalo, New York: Prometheus Books,1982), especially chapter 13, "Put Up or Shut Up," where he gives accounts of tests done on several psychics who have tried to collect the $10,000 Randi used to offer to anyone who can demonstrate any psychic power. So far, no one has collected, even though the offer is now $1,000,000!

Reed, Graham. The Psychology of Anomalous Experience : A Cognitive Approach (Buffalo, NY: Prometheus Books, 1988).

Sagan, Carl. The Demon-Haunted World: Science as a Candle in the Dark (New York: Random House, 1995).

Scott, Christopher. (1988). Remote viewing. Experientia, 44, 322–326.

Steiner, Robert A. (1989). Don't Get Taken! - Bunco and Bunkum Exposed - How to Protect Yourself  Wide-Awake Books.

Steiner, Robert A. "Fortunetelling," in The Encyclopedia of the Paranormal edited by Gordon Stein (Buffalo, N.Y.: Prometheus Books, 1996) pp. 281-290.

Stein, Gordon. editor, The Encyclopedia of the Paranormal (Buffalo, N.Y.: Prometheus Books, 1996).

Stenger, Victor J. (2002). "Meta-Analysis and the File-Drawer Effect." Skeptical Briefs.

Vistica, Gregory. "Psychics and Spooks, How spoon-benders fought the cold war," Newsweek, Dec. 11, 1995, p. 50.

Vyse, Stuart A. Believing in Magic: The Psychology of Superstition (Oxford University Press 2000).

Wiseman, Richard and Matthew Smith, "Can Animals Detect When Their Owners Are Returning Home?" British Journal of Psychology, 89:453, 1998.

Wiseman, Richard  and Ciarán O’Keeffe. 2004. "Testing Alleged Mediumship: Methods and Results," by  (paper presented to the Parapsychological Convention).

Zusne,  Leonard and Warren Jones. Anomalistic Psychology: A Study of Magical Thinking 2nd edition. (Lawrence Erlbaum Assoc. 1989).


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