A peer-reviewed article reporting a bizarre and previously unknown form of amnesia imparts valuable scientific lessons: poorly documented case reports can confuse as well as enlighten, and we should be skeptical of clinical claims modeled after Hollywood plots. It also reminds us why scientific journals need to allow for the self-correction of questionable claims.

Well-documented case reports have substantial value. As Davison and Lazarus (2007) note, case reports can raise useful questions about theories, provide preliminary data to be tested in more rigorous investigations, and “permit the investigation, although poorly controlled, of rare but important phenomena” (157).

Nevertheless, case reports of novel clinical phenomena have their limitations, especially when presented without adequate documentation. As Loftus and Guyer (2002) observed in an article in the SKEPTICAL INQUIRER, case studies “illuminate, but can also obscure the truth. In many cases, they are limited by what their reporter sees, and what their reporter leaves out. . . . To the scientist, therefore, most case studies are useful largely to generate hypotheses to be tested, not as answers to questions” (26).

To illustrate the problems of poorly documented case reports, we analyze a recent report by Smith et al. (2010) of a purportedly new and exceedingly strange memory disorder. This case was published in Neuropsychologia, one of the world’s premier outlets for neuropsychological articles.

The Apparent Discovery of a Remarkable New Form of Amnesia

Smith and colleagues (2010) described an extraordinary and unique constellation of memory aberrations. Their patient—a fifty-one-year-old woman referred to as “FL”—was involved in a car accident in 2005, during which she briefly lost consciousness. FL reported that since then she accumulates memories continually during the day but then loses all of them after one night of sleep. That is, she experiences overnight amnesia, so she must start afresh with a “blank slate” when she awakens each morning. The investigators noted that FL’s symptoms mimicked the scenario of the 2004 romantic comedy 50 First Dates, in which one of the characters, Lucy (portrayed by Drew Barrymore), suffers from overnight amnesia following a car accident.

Soon after the publication of Smith et al.’s case study, a number of websites rushed to publicize it. The website Neurocritic noted that Hollywood has a long and checkered history of presenting cases of amnesia that bear no resemblance to reality, but “that isn’t true anymore.” The British Psychological Society’s Research Digest reported that “psychologists have documented what they believe to be a clinical first—the case of an amnesic woman whose memory for new material is erased each night that she goes to sleep.” What is notable about these and other web reports is that they were virtually all offered without even a hint of skepticism. In turn, these uncritical descriptions were picked up verbatim by numerous other websites.

The Limitations of Smith et al.’s Case Report

As we will see, all of these reports neglected to mention a crucial fact: the Smith et al. case report was marked by three major limitations.

Limitation #1: Lack of Crucial Background Information

The level of detail regarding FL’s case description is unsatisfactory. The authors inform us that despite FL’s severe memory impairments, “she was able to return to her previous employment after some accommodations were made at work” (Smith et al. 2010, 2834). It is difficult to imagine any job in which recollection of all information gained after a specific date (in this case, after FL’s car accident) is inessential. Furthermore, the article suffers from a striking paucity of information about FL’s work accommodations: did they involve lessened responsibility, fewer working hours, longer breaks, more assistance, and so on? If so, such privileges might constitute an important motive for feigning memory impairments.

As appropriately skeptical readers, we need to know to what extent FL’s overnight amnesia adversely affects her everyday functioning. Nevertheless, Smith and colleagues apparently did not attempt to contact co-workers or friends to confirm that FL’s presumed memory loss has affected her daily behaviors.

Still other information provided by the authors is uninformative. For example, the fact that the patient failed to recover memories of the time after the accident while under hypnosis (2834) does not offer evidence that such memories were inaccessible to her. Hypnosis, despite popular misconception, is not a dependable technique for recovering lost memories (Lynn et al. 2003).

Smith et al. mentioned in passing FL’s involvement with the legal system following her accident. Nevertheless, they do not provide adequate details concerning this involvement. For example, did FL file a personal-injury claim? Research shows that a litigation context is associated with symptom exaggeration and misrepresentation (Faust 1996; Tolin et al. 2004). Indeed, Iverson (2005) found that patients involved in litigation display substantially lower neuropsychological performance (that is, lower scores on standardized measures of memory, attention, and problem-solving) than comparable patients who are not. This pattern suggests that their scores on neuropsychological tests may partly reflect attempts to persuade others (such as attorneys and jurors) that they deserve financial compensation.

Limitation #2: Failure to Exclude Feigning or Inadequate Motivation

A second limitation of Smith et al.’s case report is their failure to rule out feigning or a lack of motivation to remember new material (see Carone et al. 2010). In their case description, Smith and colleagues dismissed the possibility of feigning by arguing that “it was the impression of those who worked with FL that she believed that she had the memory impairment that she described” (Smith et al. 2010, 2839). Yet this reassurance is unsatisfying because subjective clinical impressions alone are known to be grossly insufficient for detecting the feigning of disorders (Rosen and Phillips 2004).

Smith et al. administered several memory tests to FL as well as to healthy participants who were instructed to simulate overnight amnesia. In many respects, the performances of the simulators paralleled that of FL, which should give us pause when interpreting the claim that her amnesia is genuine. The authors also administered several memory tasks that involved tests of learned materials following a delay of twenty-four hours. When they tested FL’s delayed memory covertly—in a way that was not transparent to her—there were clear indications that despite her purported memory difficulties, FL could reproduce material that was presented on the previous day. This performance pattern flies in the face of the overnight amnesia syndrome attributed to FL.

To their credit, Smith et al. did administer Warrington’s (1984) “Recognition Memory Test for Words and Faces” to FL. She obtained a score of 41 on the immediate recognition test; using a cutoff score ascertained in a recent study (Kim et al. 2010), this low score provides preliminary evidence that FL exerted low levels of effort on the neuropsychological tests she was administered. Nevertheless, the authors of her case description apparently overlooked this worrisome indication.

Limitation #3: Lack of Connectivity with the Scientific Literature

Absence of connectivity (Stanovich 2009), a key indicator of questionable science, occurs when investigators neglect the existing corpus of scientific knowledge. Indeed, from both scientific and theoretical perspectives, Smith et al.’s case description is puzzling. There is no known mechanism whereby memories can be acquired during the course of a day only to be wiped clean after a night’s sleep. Moreover, an abundance of literature demonstrates that certain sleep stages promote memory consolidation, whereas sleep deprivation impedes it (Walker and Van der Helm 2009). Yet Smith et al. inform readers that following a sleep-deprivation protocol, FL’s amnesic deficit somehow disappeared and that “her husband reported that she awakens 3.5 h into each night’s sleep and has been able to retain her memory for successive days with this regimen” (Smith et al. 2010, 2834).

The authors’ sleep-deprivation protocol could have afforded them a powerful tool to falsify their hypothesis. What would have happened if the treatment team allowed FL to sleep for only three-and-a-half hours or less but informed her that she had slept for six hours or more? If FL had continued to claim a lack of memories despite sleeping for only three-and-a-half hours or less, this finding would have pointed strongly in the direction of a persistent belief in amnesia in its absence or feigning amnesia rather than amnesia per se.

Hollywood and Amnesia

As we have already noted, FL’s memory loss is suspiciously similar to that of Drew Barrymore’s character in the film 50 First Dates. Interestingly, FL saw the movie several times after her accident, and she reported that Drew Barrymore was her favorite actress. Smith et al. acknowledged that FL’s multiple viewings of the film may well have shaped her beliefs about memory and, in turn, her amnesic symptoms. In the authors’ words: “The idea that memories can disappear overnight became popularized by a fictional film and may have influenced FL’s concept of how memory could fail after a car accident” (Smith et al. 2010, 2839).

Thus, according to Smith and colleagues, FL’s amnesia may reflect her belief that a person can lose all newly acquired memories after a night of sleep. This belief, in turn, may explain the paradox of FL’s reporting that she loses all of her memories overnight co-existing with her ability to retain the previous day’s knowledge when demonstrated on covert testing.

This analysis is logically confused. The term amnesia indicates a condition that can be objectively documented and goes beyond a mere belief patients hold about their memories (see Read and Lindsay 2000). If FL only believes that she suffers from a memory impairment, and her memory actually functions largely within the normal range, her condition would more accurately be described as pseudo-amnesia, not amnesia.

Baxendale (2004) noted that the overwhelming majority of films that portray amnesia do so in a grossly inaccurate fashion—with the 2000 film Memento being a noteworthy exception (see also Lilienfeld et al. 2010). For example, many films depict people with amnesia following brain trauma as having no recollection whatsoever of their identity or past, when in fact such complete loss is exceedingly rare. Other films erroneously depict people who develop amnesia as acquiring remarkable—even superhuman—powers, including extrasensory perception and other paranormal abilities. Ironically, Baxendale singled out 50 First Dates as an especially egregious example of Hollywood’s unscientific portrayal of memory loss, observing that this film “maintains a venerable movie tradition of portraying an amnesic syndrome that bears no relation to any known neurological or psychiatric condition” (Baxendale 2004, 1480).

Avoiding Erroneous Conclusions in Case Reports: Thinking Bayesian

Truzzi’s (1976, 1978) and Sagan’s (1995) maxim that extraordinary claims require extraordinary evidence makes good sense from a Bayesian standpoint, a statistical and conceptual approach that takes a priori plausibility into account when evaluating the likelihood of claims. The base rate (prevalence) of extraordinary phenomena is by definition extremely low (Atwood 2008; Goodman 1999). If a memory disorder like overnight amnesia exists, its prevalence is surely tiny relative to that of feigning, especially when real-world privileges or judicial outcomes are potentially at stake. As a consequence, the evidence needed to conclude that such a syndrome is present should be overwhelming. As medical students learn, “When you hear hoofbeats, think horses, not zebras,” an admonition to “think Bayesian” when evaluating the likelihood of diagnostic possibilities (Groopman 2007).

Wedding and Faust (1989) advised neuropsychologists to “not become overly focused on the esoteric” (258) and noted that clinicians’ preoccupation with uncommon features is an obstacle to sound clinical judgment. In the case of FL, the scientific guideline of Occam’s razor urges us to assign much higher probability to alternative explanations for her amnesia than to overnight amnesia.

Three Scientific Lessons Imparted by the Smith et al. Case Report

Lesson 1: Welcome the Publication of Case Reports, but Insist on Adequate Documentation

The case report of FL is certainly intriguing. If the existence of an entirely new form of amnesia in her case were to be confirmed, it would not only herald the discovery of a new disorder but challenge existing models of memory loss. Nevertheless, it is difficult to justify the publication of Smith et al.’s report in its present form given the absence of crucial details and failure to rule out plausible rival hypotheses for FL’s symptoms. As a general rule, journals should insist on high standards of objective documentation when publishing case reports of rare or unusual phenomena. If such documentation is unavailable, it is at the very least incumbent on authors to be circumspect in their conclusions.

Lesson 2: Widely Viewed Television Programs and Films May Influence the Presentation of Patients’ Symptoms

Psychologists and psychiatrists have long recognized that certain disorders are partly iatrogenic in origin: that is, they can be inadvertently induced by well-meaning, but mistaken, psychological or medical treatment (Lilienfeld 2007). The case of FL reminds us, however, that in today’s media-driven world, some disorders may be what we term telegenic in origin: induced at least partly by television, films, and news and entertainment media.

Dissociative identity disorder (DID), formerly called multiple personality disorder, is a likely case in point of a telegenic disorder (see Byrne 2001). Prior to 1970, there were fewer than 80 such cases reported in the world literature. Nevertheless, following the 1976 made-for-television film Sybil that starred Sally Field, who portrayed a real-life woman with a history of severe child abuse who supposedly possessed sixteen personalities (but see Rieber et al. 2002 for data calling the Sybil case into question), the number of DID cases skyrocketed into the thousands (Boor 1982). Although this finding does not prove that Sybil triggered the dramatic increase in DID cases, there are good circumstantial reasons to believe that the film played at least some causal role. For example, prior to Sybil, remarkably few individuals with DID reported a history of child abuse; following Sybil, the overwhelming majority did (Spanos 1996). Moreover, although most cases of DID prior to Sybil reported only one or two alter personalities, the mean number of DID cases in post-Sybil reports was much higher—in one study it was sixteen, precisely the number reported by Sybil (Ross et al. 1989).

Clinicians who work with individuals who report disturbances in memory and identity must therefore be cognizant of the possibility that their patients’ symptoms can be shaped by Hollywood depictions (Baxendale 2004). Because many of these portrayals are wildly inaccurate from a scientific standpoint, clinicians may be duped into accepting telegenically induced symptoms—which are merely modeled after Hollywood depictions—as reflecting entirely “new” disorders.

Lesson 3: Permit Researchers to Submit Critiques of Case Reports inthe Peer-Reviewed Literature

Editors and reviewers play crucial gatekeeper roles in evaluating whether case reports of patients displaying spectacular symptoms 1) provide sufficient detail, 2) rule out alternative explanations, 3) build on existing scientific findings and theories, and 4) refrain from launching premature diagnostic entities. Nevertheless, if journal editors elect to accept case reports even when they are suboptimal in one or more of these respects, they must at the very least afford critics the opportunity to articulate the shortcomings of those reports.

Remarkably, the journal that published the Smith et al. case, Neuropsychologia, does not accept commentaries on its case reports (or other empirical articles) and refused to even consider a rebuttal of Smith et al.’s case report for publication. Compounding the problem, several other journals (perhaps understandably) refused to consider publishing a commentary on the Smith et al. case report on the grounds that it had appeared in a different journal.

Neuropsychologia’s misguided editorial policy deprives science of one of its most valuable safeguards: self-correction (see Beyerstein 1995). When journals do not allow authors to submit critiques of case reports, they short-circuit the essential role of the peer scientific community in scrutinizing remarkable claims. In turn, they may permit questionable information to make its way into the peer-reviewed and popular literatures, allowing dubious conclusions to be disseminated with minimal qualification. The result, we suspect, is often little more than scientific obfuscation.

Postscript: Another Case of Telegenic Amnestic Syndrome?

Soon after we completed the initial draft of this article, co-author Thomas Merten saw a patient in a hospital’s neurology ward: a twenty-three-year-old male found by his girlfriend in the bathroom following a brief period of reported unconsciousness the previous week. He claimed not to recognize her or anyone else and to have no recollection of his identity. Oddly, he exhibited neither signs of marked brain damage on neuroimaging nor any neurological or neuropsychological symptoms on standardized testing. Yet the man reported that he had lost all memories, plus all of his learned abilities, such as knowing how to open a can. At the conclusion of the interview, he reported that during his previous weekend at home he had watched the movie 50 First Dates with his girlfriend. She informed him they had seen it several times in the past, but he claimed to have no memory of it.

If our speculations about “telegenic amnestic syndrome” are correct, this postscript may end up being merely the pilot episode of a host of others to follow. As they say in the television world, stay tuned.

References

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The growing popularity of intelligent design (ID) has left most scientists baffled, even exasperated. From their perspective, the match-up between Darwin’s theory of natural selection and ID would be laughable were it not so worrisome. It pits one theory backed by tens of thousands of peer-reviewed articles and consistent with multiple lines of converging genetic, physiological, and paleontological evidence against an armchair conjecture that has flown under the radar of peer review and has yet to generate a single confirmed scientific prediction. If the contest were a boxing match, the referee would surely have stopped the fight seconds after the opening bell.

Yet, to the dismay of most scientists, large swaths of the American public not only harbor serious doubts about Darwinian theory but believe that ID should be taught in science classes. In a 2005 Gallup poll, 34 percent of Americans said they believed that Darwinian theory was false and 31 percent favored ID as an explanation for the development of species. As of this writing, at least forty states are considering initiatives to include ID in public school science curricula. Early this past November, the Kansas Board of education voted to adopt standards mandating teachers to raise questions about Darwinian theory. Echoing the language of ID advocates, these standards refer to unexplained gaps in the fossil record and other purported challenges to the scientific status of this theory. (Shortly after this article was written, U.S. District Judge John Jones ruled that ID could not be taught as an alternative to Darwinian theory in Dover, Pennsylvania, public schools. It is too early to tell whether this ruling will affect popular support for ID across the country.)

In response to such developments, many scientists have expressed disdain-even ridicule-for believers in ID. Nobel Prize winner James D. Watson, co-discoverer of the structure of DNA, was quoted recently in The New York Times as saying that only people who “put their common sense on hold” doubt evolutionary theory (Wade 2005). Still other scientists have attributed malevolent intent to ID advocates. Expressing bewilderment at the ascendance of ID among the American public, one of my academic psychology colleagues abroad recently asked me, “What has happened to good sense and decency in the USA?”

Nevertheless, from the standpoint of psychological science, the only thing about ID’s popularity that should surprise us is that so many scientists are surprised by it. Of course, much of the resistance to Darwinian theory is theological, and media coverage of ID proponents has accorded nearly exclusive emphasis to the intimate connection between ID and fundamentalist Christianity. Nevertheless, religion doesn't tell the whole story.

The other reason for the public’s embrace of intelligent design is its compatibility with intuition. Contra Watson, it is Darwinian evolution, not ID, that is glaringly inconsistent with common sense. Political commentator Patrick J. Buchanan’s (2005) recent statements are illustrative in this regard. Invoking “common sense,” “experience,” and “reason,” Buchanan asked rhetorically, “How can evolution explain the creation of that extraordinary instrument, the human eye?”

Indeed, from the vantage point of commonplace intuition, it is far more plausible to believe that complex biological structures like the peacock’s tail and elephant’s trunk were shaped by a teleological force than by purposeless processes of mutation and natural selection operating over millions of years. To many laypeople, the latter explanation seems hopelessly farfetched. ID theorists have capitalized on this “argument from personal incredulity,” as biologist Richard Dawkins (1995) terms it, using the sculpted presidential faces on Mount Rushmore as a thought experiment. If an alien visiting the earth were to happen upon these faces, they ask, would it regard them as the outcome of intentional design or of unguided physical processes? The answer is obvious.

The foremost obstacle standing in the way of the public’s acceptance of evolutionary theory is not a dearth of common sense. Instead, it is the public’s erroneous belief that common sense is a dependable guide to evaluating the natural world. Even some prominent scientists and science writers have missed this crucial point. In a widely discussed article, psychologists Joaquim Krueger of Brown University and David Funder of the University of California-Riverside recently urged their colleagues to accord more credence to common sense notions of human nature (Krueger and Funder 2004). And in a New York Times op-ed this past August, science writer John Horgan (2005) called for a heightened emphasis on common sense in the evaluation of scientific theories.

Yet natural science is replete with hundreds of examples demonstrating that common sense is frequently misleading. The world seems flat rather than round. The sun seems to revolve around Earth rather than vice-versa. Objects in motion seem to slow down on their own accord, when in fact they remain in motion unless opposed by a countervailing force.

In my own discipline of psychology, striking violations of our intuitions abound (Lilienfeld 2005). Memory seems to operate like a video camera or tape recorder, but research demonstrates that memory is fallible and reconstructive. Most people believe that shifty eyes are good indicators of lying, but research reveals otherwise. Many people believe that opposites attract in relationships, but research shows that opposites tend to repel. The same goes for scores of other common sense claims regarding human nature, such as the belief that expressing anger is typically better than holding it in, that raising children in similar ways leads to marked similarities in their personalities, that most physically abused children grow up to become abusers themselves, and that the levels of psychiatric hospital admissions, crimes, and suicides increase markedly during full moons.

Of course, none of this demonstrates that common sense is worthless. When it comes to gauging our long-term emotional preferences for people and products, research suggests that we are often better off trusting our gut hunches than engaging in dry, objective analyses of the pros and cons (Gladwell 2005; Myers 2002). Yet when it comes to discerning the workings of the outside world or the three-pound world inside of our cranial cavities, common sense is an exceedingly undependable barometer of the truth.

Ironically, if scientists took the implications of evolutionary theory more seriously, they would understand why. The human brain evolved to increase the probability that the genes of the body it inhabits make their way into subsequent generations. It did not evolve to infer general principles about the operation of the natural world, let alone to understand itself. It also did not evolve to comprehend vast expanses of time, such as the unimaginable tens or hundreds of millions of years over which biological systems evolved. Consequently, it is hardly surprising that many intelligent individuals, like Patrick Buchanan, glance at the remarkably intricate biological world and conclude that it must have been produced by a designer.

To a substantial extent, the fault in the current ID wars lies not with the general public, but with scientists and science educators themselves. Generations of biology, chemistry, and physics instructors have taught their disciplines largely as collections of disembodied findings and facts. Rarely have they emphasized the importance of the scientific method as an essential toolbox of skills designed to prevent us from fooling ourselves. As Alan Cromer (1994) and Lewis Wolpert (1992) have noted, science does not come naturally to any of us, because it often requires us to think in ways that run counter to our common sense (see also McCauley 2000). Mark Twain observed that education requires us to unlearn old habits at least as much as learn new ones. Nowhere is Twain’s maxim truer than in effective science education, which asks us to unlearn our reflexive inclination to uncritically trust our perceptions.

Moreover, scientists and the skeptical community at large have long been waging the battle against pseudoscience on only a single front. They have treated each dubious claim, whether it be ID, astrology, or the latest quack herbal remedy, as an isolated thinking error to be combated. In doing so, they have forgotten that the popularity of ID is merely one example of a far broader problem, namely the American public’s embrace of pseudoscience in its myriad incarnations. This one-claim-at-a-time approach helps to explain why scientists are losing not only the ID wars, but also the broader war against public belief in pseudoscience. About a quarter of Americans believe that astrology is scientific and about half believe in extrasensory perception despite the virtually wholesale absence of evidence for either assertion. Public acceptance of alternative medicine continues to mount despite controlled studies showing that most popular alternative remedies are ineffective. Slaying each pseudoscientific dragon as it emerges is laudable and at times necessary, but as a long-term strategy against irrationality it is destined to fail.

Indeed, to win the long-term battle against pseudoscience, scientists must look beyond the narrow battles against ID. The real war they must wage is in the classroom. Specifically, scientists need to effect a sea-change in how science is taught at the junior high, high school, and college levels. They must teach students not merely the core knowledge of their subject matter, but also an understanding of why researchers developed scientific methods in the first place, namely as an essential safeguard against human error.

To do so, they must inculcate in students a profound sense of humility regarding their own perceptions and interpretations of the world. They should teach students about optical illusions, which demonstrate that our perceptions can mislead us. They should show students how their common sense notions regarding the movements of physical objects, like the trajectory of a ball emerging from a spiral, are often incorrect. They should teach students that even highly confident eyewitness reports are frequently inaccurate. Most broadly, they must counteract what Stanford psychologist Lee Ross calls “naïve realism"-the deeply ingrained notion that what we see invariably reflects the true state of nature (Ross and Ward 1996). Scientists may well emerge victorious from the current ID battles. Given that the research evidence is overwhelmingly on their side, they certainly deserve to. Yet as Dawkins (1993) reminds us, ideas can mutate at least as readily as genes. Unless scientists institute a fundamental change in how science is taught, it may be only a matter of time before a new and even more virulent variant of Intelligent Design emerges. Then scientists will again be surprised at the public’s uncritical embrace of it, while shaking their heads in disbelief at the average American’s lack of common sense.

References

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• Wolpert, L. 1992. The Unnatural Nature of Science: Why Science Does Not make (Common) Sense. Cambridge, Mass.: Harvard University Press.

Eventually, positive findings using yet another novel paradigm are reported, followed by another round of replication failures, and so on. Moreover, in contrast to the argot of what Imre Lakatos termed “progressive” scientific research programs, the lexicon of parapsychology is replete with terms describing the absence of effects. The “experimenter (shyness) effect” refers to the failure to obtain positive findings when skeptical researchers are present, the “decline effect” refers to the disappearance or marked diminution of ESP effects within a session following an initial run of positive results, and “psi missing” refers to ESP performance that is significantly worse than chance (see Gilovich, T., 1991, How We Know What Isn't So, New York: Free Press, for a good discussion). These terms underscore the absence of a crucial feature that is a hallmark of mature laboratory sciences, namely a readily transportable “experimental recipe” that can yield replicable results across independent laboratories.

This pessimistic state of affairs appeared to change, however, in 1994, when Cornell University psychologist Daryl Bem, in conjunction with the late University of Edinburgh parapsychologist Charles Honorton, published a remarkable article in Psychological Bulletin, one of psychology’s two most prestigious review journals. Bem and Honorton reported on a series of eleven studies using the "Ganzfeld” (a German word meaning “whole field”) paradigm, a method that originated in the 1930s. Subjects ("percipients”) in a Ganzfeld experiment are immersed in a uniform sensory field, typically by covering their eyes with Ping-Pong ball halves, directing a red floodlight toward their eyes, and pumping white noise into their ears through headphones. Another individual (the "sender”) located in an acoustically shielded room attempts to transmit a specific visual stimulus to the percipient, who then is asked to report all mental imagery that comes to mind. Finally, the percipient is presented with a set of several (typically four) visual stimuli, only one of which is the stimulus viewed by the sender, and asked to rate the extent to which each stimulus matches the mental imagery experienced during the session.

The logic of the Ganzfeld technique relies on the concept of the signal-to-noise ratio. The mental information ostensibly detected by ESP percipients is posited to be an extremely weak signal that is typically obscured by a large number of extraneous stimuli. By placing the percipient in a uniform sensory field, the Ganzfeld technique is hypothesized to decrease the proportion of noise relative to signal and thereby permit investigators to uncover normally weak ESP effects.

With the aid of a statistical technique termed meta-analysis, which permits researchers to quantitatively pool results across a number of studies, Bem and Honorton reported what appeared to be strong, if not convincing, evidence for ESP. The subjects in their meta-analysis obtained overall target “hit” rates of approximately 35 percent, where chance performance would be only 25 percent. Moreover, Bem and Honorton reported several psychologically meaningful predictors of Ganzfeld performance. Subjects who 1) were artistically creative (music, drama, and dance students recruited from the Julliard School), 2) extroverted, 3) had previous ESP-like experiences (but who were “novices,” i.e., had no previous experience as Ganzfeld subjects), 4) had previously studied a mental discipline, such as meditation (but who similarly were novices), and 5) received high scores on self-report indices of emotionality and perceptual orientation to the environment obtained especially high hit rates. In addition, experimental conditions using dynamic visual stimuli yielded higher hit rates than those using static visual stimuli.

Bem and Honorton’s findings, which were widely disseminated in both the popular and academic press, have stirred fresh hopes in the parapsychology community that a truly replicable method of eliciting ESP effects may at last be at hand. Moreover, they have been cited in several popular books, including Dean Radin’s The Conscious Universe, and Courtney Brown’s Cosmic Voyage, as providing very promising, if not conclusive, support for the existence of ESP.

Although some critics, like Ray Hyman, found statistical anomalies in the Bem and Honorton data set suggesting the possible existence of subtle but damaging experimental artifacts (see Hyman, R., Skeptical Inquirer, March/April 1996; and Hyman, R., Psychological Bulletin, 1994), Bem and Honorton’s meta-analysis was regarded by many as offering the most compelling laboratory evidence to date for the existence of ESP.

This is essentially where things stood until a few months ago, when Julie Milton of the University of Edinburgh and Richard Wiseman of the University of Hertfordshire published an updated meta-analysis of thirty recent Ganzfeld studies not reviewed by Bem and Honorton. Milton and Wiseman’s findings, which were published recently ("Does Psi Exist? Lack of Replication of an Anomalous Process at Information Transfer,” Psychological Bulletin 125(4): 387-391), stand in stark contrast to those of Bem and Honorton and raise serious questions concerning the replicability of the Ganzfeld findings. Specifically, Milton and Wiseman reported a mean effect size across all thirty studies of .013, which corresponds to essentially chance performance and can most charitably be described as negligible.

Moreover, Milton and Wiseman failed to replicate Bem and Honorton’s findings that a previous history of ESP-like experiences and the use of dynamic targets predicted enhanced Ganzfeld performance. (Because of insufficient information in the studies, Milton and Wiseman were unable to directly examine Bem and Honorton’s other predictors, such as extroversion.) In contrast, Milton and Wiseman did find that previous participation in a mental discipline among novices predicted enhanced Ganzfeld performance. Ironically, however, a re-examination of Bem and Honorton’s analyses revealed that this predictor was incorrectly identified as statistically significant in their original article, suggesting that the overall findings for the mental discipline variable in fact amount to another replication failure. In the words of baseball hall-of-famer Yogi Berra, Milton and Wiseman’s findings appear to be a case of “déjà vu all over again.” Seemingly replicable parapsychological findings have again proven to be disconcertingly elusive, and the experimental ESP literature has again proven to be consistently inconsistent.

Parapsychologists have already begun to raise questions regarding Milton and Wiseman’s findings and conclusions. For example, some have criticized Milton and Wiseman for including a heterogeneous set of studies in their meta-analysis, and have pointed out that several studies in their database were in fact statistically significant. Nevertheless, Milton and Wiseman reported that a statistical test of homogeneity conducted on the individual effect sizes suggested that the studies in their meta-analysis can be regarded as being drawn from the same overall “population” of studies.

It seems likely that Milton and Wiseman’s meta-analysis will not be the final word on the Ganzfeld technique, and the question of whether this technique will prove to be the replicable paradigm long sought by parapsychologists or merely another tantalizing will-o'-the-wisp is far from conclusively resolved.

It is evident, however, that the ball is now back in the court of parapsychologists, who will need to convince open-minded skeptics that the Ganzfeld technique will not go the way of J. B. Rhine’s classic Zener card studies, Targ and Puthoff’s remote viewing studies, and other superficially promising but ultimately disappointing ESP paradigms. Otherwise, it may soon be back to the drawing board for yet another paradigm.