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To bei'PnM, FRXh64@A%12Q100/08/10: CIA-RDP96-00792R000100130002-1 Still subject to final editing. Does Psi Exist? Replicable Evidence for an Anomalous Process of Information Transfer Daryl J. Bem Charles Honorton Cornell University University of Edinburgh Most academic psychologists do not yet accept the existence of psi, anomalous processes of in- formation or energy transfer (like telepathy or other forms of extrasensory perception) that are currently unexplained in terms of known physical or biological mechanisms. We believe that the replication rates and effect sizes achieved by one particular experimental method, the ganzfeld procedure, are now sufficient to warrant bringing this body of data to the attention of the wider psychological community. We review competing meta-analyses of the ganzfeld database, one by Hyman (1985), a skeptical critic of psi research, the other by Honorton (1985), a parapsychologist and major contributor to the ganzfeld database. Next we summarize the re- sults of 11 new ganzfeld studies that comply with guidelines jointly authored by Hyman and Honorton (1986). Finally, we discuss issues of replication and theoretical explanation. The term psi denotes anomalous processes of informa- tion or energy transfer, processes like telepathy or other forms of extrasensory perception that are currently unex- plained in terms of known physical or biological mecha- nisms. The: term is purely descriptive: It neither implies that such anomalous phenomena are paranormal nor con- notes anything about their underlying mechanisms. Does psi exist? Most academic psychologists don't think so. A survey of over 1,100 college professors in the United States found that 55% of natural scientists, 66% of social scientists (excluding psychologists), and 77% of academics in the arts, humanities, and education believed that ex- trasensory perception is either an established fact or a likely possibility. The comparable figure for psychologists was only 134%. Moreover, an equal number of psycholo- gists declared extrasensory perception to be an impossibil- ity, a view expressed by only 2% of all other respondents (Wagner & Monnet, 1979). Psychologists are probably more skeptical about psi for several reasons. First, we believe that extraordinary claims require extraordinary proof. And although our col- leagues from other disciplines would probably agree with Sadly, Charles Honorton died of a heart attack on November 4, 1992, nine days before this article was accepted for publication. He was 46. Parapsychology has lost one of its most valued con- tributors. I have lost a valued friend. This collaboration had its origins in a 1983 visit I made to Honorton's Psychophysical Research Laboratories (PRL) in Princeton, New Jersey, as one of several outside consultants brought in to examine the design and implementation of the ex- perimental protocols. Preparation of this article was supported, in part, by grants to Charles Honorton from the American Society for Psychical Re- search and the Parapsychology Foundation, both of New York City. The work at PRL summarized in the second half of this ar- ticle was supported by the James S. McDonnell Foundation of St. Louis, Missouri, and by the John E. Fetzer Foundation of Kala- mazoo, Michigan. Helpful comments on earlier drafts were received from Debo- rah Delany, Edwin May, Donald McCarthy, Robert Morris, John Palmer, Robert Rosenthal, Lee Ross, Jessica Utts, Philip Zim- bardo, and two anonymous reviewers. Correspondence should be addressed to Daryl J. Bem, Depart- ment of Psychology, Uris Hall, Cornell University, Ithaca, NY 14853. this dictum, we are more likely to be familiar with the methodological and statistical requirements for sustaining such claims-as well as with previous claims that failed either to meet those requirements or to survive the test of successful replication. Even for ordinary claims, our con- ventional statistical criteria are conservative. The sacred p = .05 threshold is a constant reminder that it is far more sinful to assert that an effect exists when it does not (the Type I error) than to assert that an effect does not exist when it does (the Type II error). Second, most of us distinguish sharply between phe- nomena whose explanations are merely obscure or contro- versial (e.g., hypnosis) and phenomena like psi, which would appear to fall outside our current explanatory framework altogether. (Some would characterize this as the difference between the unexplained and the inexplica- ble.) In contrast, many laypersons treat all exotic psycho- logical phenomena as epistemologically equivalent-many even consider dejh vu to be a psychic phenomenon. The blurring of this critical distinction is aided and abetted by the mass media, "hew age" books and mind-power courses, and by "psychic" entertainers who present both genuine hypnosis and fake "mindreading" in the course of a single performance. Accordingly, most laypersons would not have to revise their conceptual model of reality as radi- cally as we would in order to assimilate the existence of psi. For us, psi is simply more extraordinary. And finally, research in cognitive and social psychology has sensitized us to the errors and biases that plague in- tuitive attempts to draw valid inferences from the data of everyday experience (Gilovich, 1991; Nisbett & Ross, 1980; Tversky & Kahneman, 1971). This leads us to give virtually no probative weight to anecdotal or journalistic reports of psi-the main source cited by our academic col- leagues as evidence for their beliefs about psi (Wagner & Monnet, 1979). Ironically, however, psychologists are probably not more familiar than others with recent experimental research on psi. Like most psychological research, parapsychological research is reported primarily in specialized journals; un- like most psychological research, however, contemporary parapsychological research is not usually reviewed or summarized in psychology's textbooks, handbooks, or mainstream journals. For example, only 1 of 64 introduc- Approved For Release 2000/08/10 : CIA-RDP96-00792R000100130002-1 Approved For Releaseld / /VO ?i9' -RDP96-OT 79 09010013OOO2-1 tory psychology textbooks recently surveyed even men- tions the experimental procedure reviewed in this article, a procedure that has been in widespread use since the early 1970s (Roig, Icochea, & Cuzzucoli, 1991). Other sec- ondary sources for nonspecialists are frequently inaccu- rate in their descriptions of parapsychological research (Child, 1985; Palmer, Honorton, & Utts, 1989). This situation may be changing. Discussions of modem psi research have recently appeared in a widely-used in- troductory textbook (Atkinson, Atkinson, Smith, & Bern, 1990, 1993), two mainstream psychology journals (Child, 1985; Rao & Palmer, 1987), and a scholarly but accessible book for nonspecialists (Broughton, 1991). The purpose of the present article is to supplement these broader treat- ments with a more detailed, meta-analytic presentation of evidence issuing from a single experimental method: the ganzfeld procedure. We believe that the replication rates and effect sizes achieved with this procedure are now suf- ficient to warrant bringing. this body of data to the atten- tion of the wider psychological community. The Ganzfeld Procedure By the 1960s, a number of parapsychologists had be- come dissatisfied with the familiar ESP testing methods pioneered by J. B. Rhine at Duke University in the 1930s. In particular, they felt that the repetitive forced-choice procedure in which a subject repeatedly attempts to select the correct "target" symbol from a set of fixed-alternatives failed to capture the circumstances that characterize re- ported instances of psi in everyday life. Historically, psi has often been associated with medita- tion, hypnosis, dreaming, and other naturally occurring or deliberately induced altered states of consciousness. For example, the view that psi phenomena can occur during meditation is expressed in most classical texts on medita- tive techniques; the belief that hypnosis is a psi-conducive state dates all the way back to the days of early mes- merism (Dingwall, 1968); and cross-cultural surveys indi- cate that most reported "real-life" psi experiences are me- diated through dreams (Green, 1960; Prasad & Stevenson, 1968; Rhine, 1962; Sannwald, 1959). There are now reports of experimental evidence consis- tent with these anecdotal observations. For example, sev- eral laboratory investigators report that meditation facili- tates psi performance (Honorton, 1977). A meta-analysis of 25 experiments on hypnosis and psi conducted between 1945-1981 in 10 different laboratories suggests that hyp- notic induction also facilitates psi performance (Schechter, 1984). And dream-mediated psi was reported in a series of experiments conducted at Maimonides Medical Center in New York., and published between 1966 and 1972 (Child, 1985; Ullman, Krippner, & Vaughan, 1973). In the Maimonides dream studies, two subjects-a "receiver" and a "sender"-spent the night in a sleep labo- ratory. The receiver's brainwaves and eye movements were monitored as he or she slept in an isolated room. When the receiver entered a period of REM sleep, the ex- perimenter pressed a buzzer that signaled the sender- under the supervision of a second experimenter-to begin a sending period. The sender would then concentrate on a randomly chosen picture (the "target") with the goal of in- fluencing the content of the receiver's dream. Toward the end of the REM period, the receiver was awakened and asked to describe any dream just experi- enced. This procedure was repeated throughout the night with the same target. A transcription of the receiver's dream reports was given to outside judges who blindly rated the similarity of the night's dreams to several pic- tures, including the target. In some studies similarity rat- ings were also obtained from the receivers themselves. Across several variations of the procedure, dreams were judged to be significantly more similar to the target pic- tures than to the control pictures in the judging sets. (Failures to replicate the Maimonides results are also re- viewed by Child (1985).) These several lines of evidence suggested a working model of psi in which psi-mediated information is concep- tualized as a weak signal that is normally masked by in- ternal somatic and external sensory "noise." By reducing ordinary sensory input, these diverse psi-conducive states are presumed to raise the signal-to-noise ratio, thereby enhancing a person's ability to detect the psi-mediated in- formation (Honorton, 1969, 1977). In order to teat the hy- pothesis that a reduction of sensory input itself facilitates psi performance, investigators turned to the ganzfeld pro- cedure (Braud, Wood, & Braud, 1975; Honorton & Harper, 1974; Parker, 1975), a procedure originally introduced into experimental psychology during the 1930s to test propositions derived from Gestalt theory (Avant, 1965; Metzger, 1930). Like the dream studies, the psi ganzfeld procedure has most often been used to test for telepathic communication .between a sender and a receiver. The receiver is placed in a reclining chair in an acoustically-isolated room. Translucent ping-pong ball halves are taped over the eyes and headphones are placed over the ears; a red floodlight directed toward the eyes produces an undifferentiated vi- sual field and white noise played through the headphones produces an analogous auditory field. It is this homoge- neous perceptual environment that is called the Ganzfeld ("total field"). In order to reduce internal somatic "noise," the receiver typically also undergoes a series of progres- sive relaxation exercises at the beginning of the ganzfeld period. The sender is sequestered in a separate acoustically- isolated room, and a visual stimulus (art print, photo- graph, or brief videotaped sequence) is randomly selected from a large pool of such stimuli to serve as the target for the session. While the sender concentrates on the target, the receiver provides a continuous verbal report of his or her ongoing imagery and mentation, usually for about 30 minutes. At the completion of the ganzfeld period, the re- ceiver is presented with several stimuli (usually four) and, without knowing which stimulus was the target, is asked to rate the degree to which each matches the imagery and mentation experienced during the ganzfeld period. If the receiver assigns the highest rating to the target stimulus, it is scored as a "Wt.' Thus, if the experiment employs judging pools containing four stimuli (the target and three "decoys" or control stimuli), then the hit rate expected by chance is .25. The ratings can also be analyzed in other ways; for example, they can be converted to ranks or standardized scores within each set and analyzed para- metrically across sessions. And, as with the dream stud- ies, the similarity ratings can also be made by outside judges using transcripts of the receiver's mentation re- Meta-analvses of the Ganzfeld Database In 1985 and 1986, the Journal of Parapsychology de- voted two entire issues to a critical examination of the Approved For Release 2000/08/10 : CIA-RDP96-00792ROO0100130002-1 Approved For Relea?2.9DO k V0 1R01P96 000100130002-1 ganzfeld database. The 1985 issue comprised two contri- butions: (a) a meta-analysis and critique by Ray Hyman (1985), a cognitive psychologist and skeptical critic of parapsychological research; and (b) a competing meta- analysis and :rejoinder by Charles Honorton (1985), a parapsychologist and major contributor to the ganzfeld database. The 1986 issue contained four commentaries on the Hyman-Honorton exchange, a joint communique by Hyman and Honorton, and six additional commentaries on the joint communique itself. We summarize the major issues and conclusions here. Replication Rates By study. Hyman's meta-analysis covered 42 psi ganz- feld studies reported in 34 separate reports written or published from 1974 through 1981. One of the first prob- lems he discovered in the database was multiple analysis. As noted above, it is possible to calculate several indices of psi performance in a ganzfeld experiment and, further, to subject those indices to several kinds of statistical treat- ment. Many investigators reported multiple indices or ap- plied multiple statistical tests without adjusting the crite- rion significance level for the number of tests conducted. Worse, some may have "shopped" among the alternatives until finding one that yielded a significantly successful outcome. Honorton agreed that this was a problem. Accordingly, Honorton applied a uniform test on a common index across all studies from which the pertinent datum could be extracted, regardless of how the investiga- tors had analyzed the data in the original reports. He se- lected the proportion of hits as the common index because it could be calculated for the largest subset of studies: 28 of the 42 studies. The hit rate is also a conservative index because it discards most of the rating information; a sec- ond place ranking-a "near miss"-receives no more credit than a last place ranking. Honorton then calculated the exact binomial probability and its associated z score for each study. Of the 28 studies, 23 (82%) had positive z scores (p = 4.6 x 10-4 exact binomial test with p = q = .5). Twelve of the studies (43%) had z scores that were independently significant at the 5% level (p = 3.5 x 10-9 ' binomial test with n = 28 studies, p = .05, and q = .95) and 7 of the studies (25%) were independently significant at the 1% level (p = 9.8 x 1(r-9). The composite Stouffer z score across the 28 studies was 6.60 (p = 2.1 x 1011).1 A more conservative estimate of significance can be obtained by including 10 additional studies that also used the relevant judging procedure but did not report hit rates. If we as- sign these studies a mean z. score of zero, then the Stouffer z across all 38 studies becomes 5.67 (p = 7.3 x 109). Thus, whether one considers only the studies for which the relevant information is available or includes a null es- timate for the additional studies where the information is not available, the aggregate results cannot reasonably be attributed to chance. And by design, the cumulative out- come reported here cannot be attributed to the inflation of significance levels through multiple analysis. By laboratory. One objection to estimates like those above is that studies from a common laboratory are not 1Stouffer's z is computed by dividing the sum. of the z scores for the individual studies by the square root of the number of studies (Rosenthal, 1978)?. independent of one another (Parker, 1978). Thus it is pos- sible for one or two investigators to be disproportionately responsible for a high replication rate while other, inde- pendent investigators are unable to obtain the effect. The ganzfeld database is vulnerable to this possibility. The 28 studies providing hit rate information were con- ducted by investigators in 10 different laboratories. One laboratory contributed nine of the studies; Honorton's own laboratory contributed five; two other laboratories con- tributed three each; two contributed two each; and the remaining four laboratories each contributed one. Thus half of the studies were conducted by only two laborato- ries, one of them Honorton's own. Accordingly, Honorton calculated a separate Stouffer z score for each laboratory. Significantly positive outcomes were reported by 6 of the 10 laboratories and the com- bined result across laboratories yielded a z of 6.16 (p = 3.6 x 10-10). Even if all the studies conducted by the two most prolific laboratories are discarded from the analysis, the Stouffer z across the eight other laboratories remains significant (z = 3.67,p = 1.2 x 10-4). Four of these studies are significant at the 1% level (p = 9.2 x 10-6, binomial test with n = 14 studies, p = .01, and q = .99), and each was contributed by a different laboratory. Thus, even though the total number of laboratories in this database is small, a majority of them have reported significant studies, and the significance of the overall ef- fect does not depend on just one or two of them. Selective Reporting In recent years, behavioral scientists have become in- creasingly aware of the "file-drawer" problem, the likeli- hood that successful studies are more likely to be pub- lished than unsuccessful studies-which are more likely to be consigned to the file drawers of their disappointed investigators (Bozarth & Roberts, 1972; Sterling, 1959). Parapsychologists were among the first to become sensi- tive to the problem; and, in 1975, the Parapsychological Association Council adopted a policy opposing the selec- tive reporting of positive outcomes. As a consequence, negative findings have been routinely reported at the As- sociation's meetings and in its affiliated publications for almost two decades now. As we have already seen, more than half of the ganzfeld studies included in the meta- analysis yielded outcomes whose significance falls short of the conventional .05 level. There is a variant of the selective reporting problem which arises from what Hyman (1985) has termed the "retrospective study." An investigator conducts a small set of exploratory trials. If they yield null results, they remain "exploratory" and never become part of the official record; if they happen to yield positive results, they get defined as a study after the fact and are submitted for publication. In support of this possibility, Hyman notes that there are more significant studies in the database with fewer than 20 trials than one would expect under the assumption that, all other things being equal, statistical power should increase with the square root of the sample size. Although Honorton questions the assumption that "all other things" are in fact equal across the studies and disagrees with Hyman's particular statistical analysis, he does agree that there is an apparent clustering of significant studies with fewer than 20 trials. (Out of the complete ganzfeld Approved For Release 2000/08/10 : CIA-RDP96-00792R000100130002-1 Approved For ReleaE 1blF4 i t I 1 00100130002-1 database of 42 studies, 8 have fewer than 20 trials, and 6 of these report statistically significant results.) Because it is impossible, by definition, to know how many unknown studies-exploratory or otherwise-are languishing in file drawers somewhere, the major tool for estimating the seriousness of selective reporting problems has become some variant of Rosenthal's "file drawer" statistic, an estimate of how many unreported studies with z scores of zero would be required to exactly cancel out the significance of the known database (Rosenthal, 1979). For the 28 direct-hit ganzfeld studies alone, this es- timate is 423 fugitive studies, a ratio of unreported-to-re- ported studies of approximately 15 to 1. When it is re- called that a single ganzfeld session takes over an hour to conduct, it is not surprising that-despite his concern with the retrospective study problem-Hyman concurs with Honorton and other participants in the published debate that selective reporting problems cannot plausibly account for the overall statistical significance of the psi ganzfeld database (Hyman & Honorton, 1986).2 Methodological Flaws If the most frequent criticism of parapsychology is that it has not produced a replicable psi effect, the second most frequent criticism is that many, if not most, psi experi- ments have inadequate controls and procedural safe- guards. A frequent charge is that positive results emerge primarily from. initial, poorly controlled studies and then vanish as better controls and safeguards are introduced. Fortunately, meta-analysis provides a vehicle for empir- ically evaluating the extent to which methodological flaws may have contributed to artifactual positive outcomes across a set of studies. First, ratings are assigned to each study that index the degree to which particular method- ological flaws are or are not present; these ratings are then correlated with the studies' outcomes. Large positive correlations constitute evidence that the observed effect may be artifactual. In psi research, the most fatal flaws are those that might permit a subject to obtain the target information in normal sensory fashion, either inadvertently or through deliberate cheating. This is called the problem of sensory leakage. Another potentially serious flaw is inadequate randomization of target selection. Sensory leakage. Because the ganzfeld is itself a percep- tual isolation procedure, it goes a long way toward elimi- nating potential sensory leakage during the ganzfeld por- tion of the session. There are, however, potential channels of sensory leakage following the ganzfeld period. For ex- ample, if the experimenter who interacts with the receiver knows the identity of the target, he or she could bias the receiver's similarity ratings in favor of correct identifica- tion. Only one study in the database contained this flaw, a study in which i3ubjects actually performed slightly below chance expectation. Second, if the stimulus set given to the receiver for Judging contains the actual physical target handled by the sender during the sending period, there might be cues (e.g., fingerprints, smudges, or temperature differences) that could differentiate the target from the 2A 1980 survey of parapsychologists uncovered only 19 com- pleted but unreported ganzfeld studies. Seven of these had achieved significantly positive results, a proportion (.37) very similar to the proportion of independently significant studies in the meta-analysis (.43) (Blackmore, 1980). decoys. Moreover, the process of transferring the stimulus materials to the receiver's room itself opens up other po- tential channels of sensory leakage. Although contempo- rary ganzfeld studies eliminate both of these possibilities by using duplicate stimulus sets, some of the earlier stud- ies did not. Independent analyses by Hyman and Honorton agreed that there was no correlation between inadequacies of se- curity against sensory leakage and study outcome. Honor- ton further reported that if studies that failed to use du- plicate stimulus sets were discarded from the analysis, the remaining studies are still highly significant (Stouffer z=4.35,p=6.8x10) Randomization. In many psi experiments, the issue of target randomization is critical because systematic pat- terns in inadequately randomized target sequences might be detected by subjects during a session or might match subjects' pre-existing response biases. In a ganzfeld study, however, randomization is a much less critical issue be- cause only one target is selected during the session and most subjects serve in only one session. The primary con- cern is simply that all targets be sampled about equally over the course of the study. Similar considerations gov- ern the second randomization, which takes place after the ganzfeld period and determines the sequence in which the target and decoys are presented to the receiver (or exter- nal judge) for judging. Nevertheless, Hyman and Honorton disagreed over the findings here. Hyman claimed there was a correlation be- tween flaws of randomization and study qutcome; Honor- ton claimed there was not. The sources of this disagree- ment were in conflicting definitions of flaw categories, in the coding and assignment of flaw ratings to individual studies, and in the subsequent statistical treatment of those ratings. Unfortunately, there have been no ratings of flaws by independent raters who were blind to the studies' out- comes (Morris, 1991). Nevertheless, none of the contribu- tors to the subsequent debate concurred with Hyman's conclusion whereas four nonparapsychologists-two statisticians and two psychologists-explicitly concurred with Honorton's conclusion (Harris & Rosenthal, 1988b; Saunders, 1985; Utts, 1991a). For example, Harris and Rosenthal (one of the pioneers in the use of meta-analysis in psychology) used Hyman's own flaw ratings and failed to find any significant relationships between flaws and study outcomes in each of two separate analyses: "Our analysis of the effects of flaws on study outcome lends no support to the hypothesis that Ganzfeld research results are a significant function of the set of flaw variables" (1988b, p. 3). (For a more recent exchange over Hyman's analysis, see Hyman (1991), Utts (1991a), and Utts (1991b).) Effect Size Some critics of parapsychology have argued that even if current laboratory-produced psi effects turn out to be replicable and non-artifactual, they are too small to be of theoretical interest or practical importance. We do not be- lieve this to be the case for the psi ganzfeld effect. In psi ganzfeld studies, the hit rate itself provides a straightforward descriptive measure of effect size, but this cannot be compared directly across studies because they do not all use a four-stimulus judging set and, hence, do Approved For Release 2000/08/10 : CIA-RDP96-00792R000100130002-1 Approved For Rele 0 & 9 - p?000100130002-1 not all have a chance baseline of .25. The next most obvi- ous candidate, the difference in each study between the hit rate observed and the hit rate expected under the null hypothesis, is also intuitively descriptive but is not appro- priate for statistical analysis because not all differences between proportions that are equal are equally detectable (e.g., the power to detect the difference between .55 and .25 is different from the power to detect the difference be- tween .50 and.20). In order to provide a scale of equal detectability, Cohen (1988) devised the effect size index h, which performs an aresine transformation on the proportions before calculat- ing their difference. Cohen's h is quite general and can as- sess the difference between any two proportions drawn from independent samples or between a single proportion and any specified hypothetical value. For the 28 studies examined in the meta-analyses, h is .28, with a 95% confi- dence interval from .11 to .45. But because values of h do not provide an intuitively descriptive scale, Rosenthal and Rubin (1989; Rosenthal, 1991) have recently suggested a new index, which ap- plies specifically to one-sample, multiple-choice data of the kind obtained in ganzfeld experiments. In particular, n expresses all hit rates as the proportion of hits that would have been obtained if there had been only two equally likely alternatives-essentially a coin flip. Thus, is ranges from 0 to 1, with .5 expected under the null hy- pothesis. The formula is: P(k - 2) + 1 where P is the raw proportion of hits and k is the number of alternative choices available. Because is has such a straightforward intuitive interpretation, we will use it (or its conversion back to an equivalent four-alternative hit rate) throughout this article whenever it is applicable. For the 28 studies examined in the meta-analyses, the mean value of it is .62, with a 95% confidence interval from .55 to .69. This corresponds to a four-alternative hit rate of 35%, with a 95% confidence interval from 28% to 43%. Cohen (1988, 1992) has also categorized effect sizes into small, medium, and large, where medium denotes an ef- fect size that should be apparent to the naked eye of a careful observer. For a statistic like n, which indexes the deviation of a proportion from .5, Cohen considers .65 to be a medium effect size: A statistically unaided observer should be able! to detect the bias of a coin that comes up heads on 65% of the trials. Thus, at .62, the psi ganzfeld effect size falls just short of Cohen's naked-eyeball crite- rion. From the phenomenology of the ganzfeld experi- menter, the corresponding hit rate of 35% implies that he or she will see a subject obtain a hit approximately every third session rather than every fourth. It is also instructive to compare the psi ganzfeld effect with the results of a recent medical study that sought to determine whether aspirin can prevent heart attacks (Steering Committee of the Physicians' Health Study Re- search Group, 1988). The study was discontinued after six years because it was already clear that the aspirin treat- ment was effective (x2 = 25.01, p < .00001) and it was con- sidered unethical to keep the control group on placebo medication. The study was widely publicized as a major medical breakthrough. But despite its undisputed reality and practical importance, the size of the aspirin effect is quite small: Taking aspirin reduces the probability of suf- fering a heart attack by only 0.008. The corresponding ef- fect size (h) is .068-about 1/3 to 1/4 the size of the psi ganzfeld effect (Atkinson et al., 1993, p. 236; Utts, 1991b). In sum, we believe that the psi ganzfeld effect is large enough to be of both theoretical interest and potential practical importance. Experimental Correlates of the Psi Ganzfeld Effect We saw above that the technique of correlating vari- ables with effect sizes across studies can help to assess whether methodological flaws might have produced arti- factual positive outcomes. The same technique can be used more affirmatively to explore whether an effect varies systematically with conceptually relevant varia- tions in experimental procedure. The discovery of such correlates can help to establish an effect as genuine, sug- gest ways of increasing replication rates and effect sizes, and enhance the chances of moving beyond the simple demonstration of an effect to its explanation. This strat- egy is only heuristic, however. Any correlates discovered must be considered quite tentative, both because they emerge from post hoc exploration and because they neces- sarily involve comparisons across heterogeneous studies that differ simultaneously on many interrelated variables, known and unknown. Two such correlates emerged from the meta-analyses of the psi ganzfeld effect. Single versus multiple-image targets. Although most of the 28 studies in the meta-analysis used single pictures as targets, 9 of the studies (conducted by three different in- vestigators) used View Master stereoscopic slide reels which presented multiple images focused on a central theme. Studies using the View Master reels produced sig- nificantly higher hit rates than did studies using the sin- gle-image targets (50% vs. 34%), t (26) = 2.22, p = .035, two-tailed. Sender/receiver pairing. In 17 of the 28 studies, partici- pants were free to bring in friends to serve as senders. In 8 studies, only laboratory-assigned senders were em- ployed. (Three studies used no sender.) Unfortunately, there is no record of how many participants in the former studies actually brought in friends. Nevertheless, those 17 studies (by six different investigators) had significantly higher hit rates than did the studies that used only labo- ratory-assigned senders (44% vs. 26%), t (23) = 2.39, p = .025, two-tailed. The Joint Communique Following their published exchange in 1985, Hyman and Honorton agreed to contribute a joint communique to the subsequent discussion which was published in 1986. First they set forth their areas of agreement and dis- agreement: We agree that there is an overall significant effect in this data base that cannot reasonably be explained by selective reporting or multiple analysis. We continue to differ over the degree to which the effect constitutes evidence for psi, but we agree that the final verdict awaits the outcome of fu- ture experiments conducted by a broader range of investiga- tors and according to more stringent standards. (Hyman & Honorton, 1986, abstract, p. 351) Approved For Release 2000/08/10 : CIA-RDP96-00792R000100130002-1 Approved For Rele ~a ,4%TRRR000100130002-1 They then spelled out in detail the "more stringent standards" they believed should govern future experi- ments. These include strict security precautions against sensory leakage, testing and documentation of randomiza- tion methods for selecting targets and sequencing the judging pool, statistical correction for multiple analyses, advance specification of the status of the experiment (e.g., pilot study, confirmatory experiment), and full documen- tation in the published report of the experimental proce- dures and the status of statistical tests (e.g., pre-planned or post hoc). The NRC Report In 1988, the National Research Council (NRC) of the National Academy of Sciences released a widely publi- cized report commissioned by the U. S. Army which as- sessed several controversial technologies for enhancing human performance, including accelerated learning, neu- rolinguistic programming, mental practice, biofeedback, and parapsychology (Druckman & Swets, 1988; summa- rized in Swets & Bjork, 1990). The report's conclusion concerning parapsychology was quite negative: 'Me Committee finds no scientific justification from research conducted over a period of 130 years for the existence.of parapsychological phenomena" (p. 22). An extended refutation strongly protesting the Commit- tee's treatment of parapsychology has been published elsewhere (Palmer et al., 1989). The pertinent point here is simply that the NRC's evaluation of the ganzfeld stud- ies does not reflect an additional, independent examina- tion of the ganzfeld database but is based on the same meta-analysis by Hyman that we have discussed in this article. Hyman chaired the NRC's Subcommittee on Parapsy- chology; and, although he had concurred with Honorton two years earlier in their joint communique that "there is an overall significant effect in this data base that cannot reasonably be explained by selective reporting or multiple analysis" (p. 351) and that "significant outcomes have been produced by a number of different investigators" (p. 352), neither of these points is acknowledged in the Committee's report. The NRC also solicited a background paper from Harris and Rosenthal (1988a), who provided the Committee with a comparative methodological analysis of the five contro- versial areas listed above. Harris and Rosenthal noted that of these areas, "only the Ganzfeld ESP studies [the only psi studies they evaluated] regularly meet the basic requirements of ,sound experimental design" (p. 53), and they concluded that "it would be implausible to entertain the null given the combined p from these 28 studies. Given the various problems or flaws pointed out by Hy- man and Honorton...we might estimate the obtained ac- curacy rate to be about 1/3...when the accuracy rate ex- pected under the null is 1/4" (p. 61).3 The Autoganzfeld Studies In '1983, Honorton and his colleagues initiated a new series of ganzfeld studies designed to avoid the method- ological problems he and others had identified in earlier studies (Honorton, 1979; Kennedy, 1979). These studies complied with all the detailed guidelines that he and Hy- man were to publish later in their joint communique. The program continued until September of 1989, when a loss of funding forced the laboratory to close. The major innovations of the new studies were the com- puter control of the experimental protocol-hence the name "autoganzfeld"-and the introduction of videotaped film clips as target stimuli. Method4 The basic design of the autoganzfeld studies was the same as that described earlier: A receiver and sender were sequestered in separate, acoustically-isolated chambers. Following a 14-minute period of progressive relaxation, the receiver underwent ganzfeld stimulation while de- scribing his or her thoughts and images aloud for 30 min- utes. Meanwhile, the sender concentrated on a randomly selected target. At the end of the ganzfeld period, the re- ceiver was shown four stimuli and, without knowing which of the four had been the target, rated each stimulus for its similarity to his or her mentation during the ganzfeld. The targets consisted of 80 still pictures (Static Targets) and 80 short video segments complete with squndtracks (Dynamic Targets), all recorded on videocassette. The static targets included art prints, photographs, and mag- azine advertisements; the dynamic targets included ex- cerpts of approximately one minute duration from motion pictures, TV shows, and cartoons. The 160 targets were arranged in judging sets of four static or four dynamic targets each, constructed to minimize similarities among targets within a set. Target selection and presentation. The VCR containing the taped targets was interfaced to the controlling com- puter, which selected the target and controlled its re- peated presentation to the sender during the ganzfeld pe- riod, thus eliminating the need for a second experimenter to accompany the sender. Following the ganzfeld period, the computer randomly sequenced the four-clip judging pool and presented it to the receiver on a TV monitor for judging. The receiver used a computer game paddle to make his or her ratings on a 40-point scale which ap- peared on the TV monitor after each clip was shown. The receiver was permitted to see each clip and to change the ratings repeatedly until he or she was satisfied. The com- puter then wrote these and other data from the session into a file on a floppy disk. At that point, the sender moved to the receiver's chamber and revealed the identity of the target to both the receiver and the experimenter. Note that the experimenter did not even know the identity of the four-clip judging pool until it was displayed to the receiver for judging. 3In a troubling development, the chair of the NRC Committee phoned Rosenthal and asked him to delete the parapsychology section of the paper (R. Rosenthal, private communication, September 15, 1992). Although Rosenthal refused to do so, that section of the Harris-Rosenthal paper is nowhere cited in the NRC report. 4Because Honorton and his colleagues have complied with the Hyman-Honorton specification that experimental reports be suf- ficiently complete to permit others to reconstruct the investiga- tor's procedures, readers who wish to know more detail than we provide here are likely to find whatever they need in the archival publication of these studies in the Journal of Parapsychology (Honorton et al., 19901 Approved For Release 2000/08/10 : CIA-RDP96-00792R000100130002-1 Approved For Rel OOrClAiIU3F% O!9RROOO1OO13OOO2-1 Randomization. The random selection of the target and sequencing of the judging pool were controlled by a noise- based random number generator interfaced to the com- puter. Extensive testing confirmed that the generator was providing a uniform distribution of values throughout the full target range (1-160), a uniform distribution of targets from among the four alternatives within each judging set, and a uniform distribution of judging sequences from among the 24 permutations of 4 stimuli. Additional control features. Both the receiver's and sender's rooms were sound-isolated, electrically-shielded chambers with single-door access that could be continu- ously monitored by the experimenter. There was two-way intercom communication between the experimenter and the receiver but only one-way communication into the sender's room; thus neither the experimenter nor the re- ceiver could monitor events inside the sender's room. The archival record for each session includes an audio tape containing the receiver's mentation during the ganzfeld period and all verbal exchanges between the experimenter and the receiver throughout the experiment. The automated ganzfeld protocol has been examined by several dozen parapsychologists and behavioral re- searchers from other fields, including well-known critics of parapsychology. Many have participated as subjects or observers. All have expressed satisfaction with the han- dling of security issues and controls. Parapsychologists have often been urged to employ ma- gicians as consultants to ensure that the experimental protocols are not vulnerable either to inadvertent sensory leakage or to deliberate cheating. Two "mentalists," magi- cians who specialize in the simulation of psi, have exam- ined the autoganzfeld system and protocol. Ford Kross, a professional mentalist and officer of the mentalist's pro- fessional organization, the Psychic Entertainers Associa- tion, provided the following written statement "In my pro- fessional capacity as a mentalist, I have reviewed Psy- chophysical Research Laboratories' automated ganzfeld system and found it to provide excellent security against deception by subjects" (private communication, May, 1989). The first author of this article has also performed as a mentalist for many years and is a member of the Psychic Entertainers Association. As noted in the author footnote, this article has its origins in a 1983 visit he made to Hon- orton's laboratory, where he was asked to critically exam- ine the research protocol from the perspective of a mental- ist, a research psychologist, and a subject. Needless to say, this article would not exist if he did not concur with Ford Kross's assessment of the security procedures. Experimental Studies Altogether 100 men. and 141 women participated as re- ceivers in 355 sessions during the research program. The participants ranged in age from 17 to 74 years (mean = 37.3, SD = 11.8), with a mean formal education of 15.6 years (SD = 2.0). Eight separate experimenters, including Honorton, conducted the studies. The experimental program included three pilot and eight formal studies. Five of the formal studies employed novice (first-time) participants who served as the receiver in one session each. The remaining three formal studies employed experienced participants. Pilot Studies. Sample sizes were not preset in the three pilot studies. Study 1 comprised 22 sessions and was con- ducted during the initial development and testing of the autoganzfeld system. Study 2 comprised 9 sessions testing a procedure in which the experimenter, rather than the receiver, served as the judge at the end of the session. Study 3 comprised 36 sessions and served as practice for participants who had completed the allotted number of sessions in the ongoing formal studies but who wanted additional ganzfeld experience. This study also included several demonstration sessions when TV film crews were present. Novice Studies. Studies 101-104 were each designed to test 50 participants who had had no prior ganzfeld experi- ence; each participant served as the receiver in a single ganzfeld session. Study 104 included 16 of 20 students re- cruited from the Juilliard School of Music in New York City in order to test an artistically gifted sample. Study 105 was initiated to accommodate the overflow of partici- pants who had been recruited for Study 104, including the four remaining Juilliard students. Sample size for this study was set to 25, but only 6 sessions had been com- pleted when the laboratory closed. For purposes of exposi- tion, we have divided the 56 sessions from Studies 104 and 105 into two parts: Study 104/105 (a) comprises the 36 non-Juilliard participants; Study 104/105 (b) comprises the 20 Juilliard students Study 201. This study was designed to retest the most promising participants from the previous studies. The number of trials was set to 20, but only 7 sessions with 3 participants had been completed when the laboratory closed. Study 301. This study was designed to compare static and dynamic targets. Sample size was set to 50 sessions. Twenty-five experienced participants each served as the receiver in two sessions. Unknown to the participants, the computer control program was modified to ensure that they would each have one session with a static target and one session with a dynamic target. Study 302. This study was designed to examine a dy- namic target set which contained one target that had of- ten been correctly identified in the previous studies and another target that had never been correctly identified. The study involved experienced participants who had had no prior experience with this particular target set and who were unaware that only one target set was being sampled. Each served as the receiver in a single session. The design called for the study to continue until 15 ses- sions were completed with each of the targets, but only twenty-five sessions had been completed when the labora- tory closed. The 11 studies just described comprise all sessions con- ducted during the 6-1/2 years of the program. There is no "file drawer" of unreported sessions. Results Overall hit rate. As in the earlier meta-analysis, re- ceivers' ratings were analyzed by tallying the proportion of hits achieved and calculating the exact binomial prob- ability for the observed number of hits compared with chance expectation of .25. As noted above, 241 partici- pants contributed 355 sessions. For reasons discussed be- low, Study 302 is analyzed separately, reducing the num- ber of sessions in the primary analysis to 330. As Table 1 shows, there were 106 hits in the 330 ses- sions, a hit rate of 32% (z = 2.85, p = .002, one-tailed), with a 95% confidence interval from 30% to 35%. This cor- Approved For Release 2000/08/10 : CIA-RDP96-00792ROO0100130002-1 Approved For Rel ,O / q - QQ17R000100130002-1 Table 1 Outcome by Study Study Study type subjects trials hits hits 1 Pilot 19 22 8 36 .62 .99 2 Pilot 4 9 3 33 .60 .25 3 Pilot 25 36 10 28 .54 .22 101 Novice 50 50 12 24 .47 -.30 102 Novice 50 50 18 36 .63 1.60 103 Novice 50 50 15 30 .55 .67 104/105 (a) Novice 36 36 12 33 .60 .97 104/105 (b) Juilliard Sample 20 20 10 50 .75 2.20 201 Experienced 3 7 3 43 .69 .69 301 Experienced 25 50 15 30 .56 .67 302 Experienced 25 25 16 44a .70a 2.02a Overall (Studies 1-301) Note. Zscores are based on the exact binomial probability with p = .25 and q = .75. aCorrected for maximum possible response bias. Hit rate actually observed was 64%. responds to an effect size (id of .59, with a 95% confidence interval from .53 to .64. Table 1 also shows that when Studies 104 and 105 are combined and re-divided into the non-Juilliard and Juil- hard samples, 9 of the 10 studies yield positive effect sizes, with a mean effect size (7r) of .61, t (9) = 4.35, p = .0009, one-tailed. This effect size is equivalent to a four-al- ternative hit rate of 34%. Alternatively, if we retain Stud- ies 104 and 105 as separate studies, 9 of the 10 studies again yield positive effect sizes, with a mean effect size (1r) of .62, t (9) = 3.137, p = .003, one-tailed. This effect size is equivalent to a four-alternative hit rate of 35% and is identical to that found across the 28 studies of the earlier meta-analysis.5 Considered together, sessions with novice participants (Studies 101-105) yielded a statistically significant hit rate of 32.5% (p = .009), which is not significantly differ- ent from the 31.6% hit rate achieved by experienced par- ticipants in Studies 201 and 301. And finally, each of the 8 experimenters also achieved a positive effect size, with a mean it of .60, t (7) = 3.44, p = .005, one-tailed. 5As noted above, the laboratory was forced to close before three of the formal studies could be completed. If we assume that the remaining trials in Studies 105 and 201 would have yielded only chance results, this would reduce the overall z for the first 10 autoganzfeld studies from 2.85 to 2.73 (p = .003). Thus, inclusion of the two incomplete studies does not pose an optional stopping problem. The third incomplete study, Study 302, is discussed below. The Juilliard sample. There are several reports in the literature of a relationship between creativity or artistic ability and psi performance (Schmeidler, 1988). In order to explore this possibility in the ganzfeld setting, 10 male and 10 female undergraduates were recruited from the Juilliard School of Music in New York City. Of these, 8 were music students, 10 were drama students, and 2 were dance students. Each served as the receiver in a single session in Studies 104 or 105. As shown in Table 1, these students achieved a hit rate of 50% (p = .014), one of the five highest hit rates ever reported for a single sample in a ganzfeld study. The musicians were particularly suc- cessful: Six of the eight (75%) successfully identified their targets (p = .004). Further details about this sample and their ganzfeld performance are reported in Schlitz and Honorton (1992). Study size and effect size. There is a significant negative correlation across the 10 studies listed in Table 1 between the number of sessions in a study and its effect size (rr): r = -.64, t (8) = 2.36, p < .05, two-tailed. This is reminiscent of Hyman's discovery that the smaller studies in the orig- inal ganzfeld database were disproportionately likely to report statistically significant results. He interpreted this finding as evidence for a bias against the reporting of small studies that fail to achieve significant results. A similar interpretation cannot be applied to the auto- ganzfeld studies, however, because there are no unre- ported sessions. One reviewer of this article suggested that the negative correlation might reflect a decline effect in which earlier sessions of a study are more successful than later ses- Approved For Release 2000/08/10 : CIA-RDP96-00792R000100130002-1 Approved For Relea &PMWIQ JkAgR9&pgpi?000100130002-1 Table 2 Study 302: Proportion of Sessions in which Each Video Clip was Ranked First when it was a Target and when it was a Decoy Relative Ranked First Ranked First Fisher's Frequency as Target when Target when Decoy Difference Exact p Tidal Wave .28 .57 .11 +.46 .032 (7/25) (4/7) (2/18) Snakes .12 .67 .05 +.62 .029 (3/25) (2/3) (1/22) High-Speed Sex .16 .25 .05 +.20 .300 (4/25) (1/4) (1/21) Bugs Bunny .44 .82 .36 +.46 .027 (11125) (9/11) (5/14) .14 +.44 sions. If there were such an effect, then studies with fewer sessions would show larger effect sizes because they would end before a decline could set in. To check this pos- sibility, we computed point-biserial correlations between hits (= 1) or misses (= 0) and the session number within each of the 10 studies. All of the correlations hovered around zero; six were positive, four were negative, and the overall mean was +.03, indicating that hits were actually slightly more likely to occur in later sessions of a study than in earlier ones. An inspection of Table 1 reveals that the negative corre- lation derives primarily from the two studies with the largest effect sizes: the 20 sessions with the Juilliard stu- dents and the 7 sessions of Study 201, the study specifi- cally designed to retest the most promising participants from the previous studies. Accordingly, we believe that the larger effect sizes of these two studies-and hence the significant negative correlation between number of ses- sions and effect size-reflects a genuinely higher psi abil- ity of participants in these two small but highly selected samples. Study 302. tell of the studies except Study 302 randomly sampled from a pool of 160 static and dynamic targets. Study 302 sampled from a single, dynamic target set which contained one video clip that had been correctly identified several times in the previous ten studies-a scene of a tidal wave from the movie Clash of the Titans- and one clip that had never been correctly identified-a high-speed sex scene from Clockwork Orange. The set also contained a scene of crawling snakes from a TV documen- tary and a scene from a Bugs Bunny cartoon. The experimental design called for this study to con- tinue until each of the clips had served as the target 15 times. Unfortunately, the premature termination of this study at 25 sessions left an imbalance in the frequency with which each clip had served as the target. This means that the chance expectation of .25 used as the baseline for evaluating the results in the other studies cannot be ap- plied to this study. More importantly, it means that the high hit rate observed (64%) could well be inflated by re- sponse biases. ' To illustrate, water imagery is frequently reported by receivers in ganzfeld sessions whereas sexual imagery is rarely reported. (It is reasonable to suppose that some participants might be reluctant both to report sexual im- agery and to give the highest rating to the sex-related clip.) If a video clip containing popular imagery (like wa- ter) happens to appear as a target more frequently than a clip containing unpopular imagery (like sex), a high hit rate might simply reflect the coincidence of those frequen- cies of occurrence with participants' response biases. And, as the first column of Table 2 reveals, the tidal wave clip did in fact appear more frequently as the target than did the sex clip. The Bugs Bunny clip was even more frequent, appearing as the target in 11 of the 25 (44%) sessions. We can assess the damage in two ways. First, we can ask for each of the four clips whether it was selected as the target (i.e., ranked in first place) significantly more frequently when it was the target than when it was one of the three control clips (decoys). This comparison, which controls for the baseline popularity of the themes and images within each clip, is shown in the remaining columns of Table 2. As can be seen, each of the four clips was selected as the target relatively more frequently when it was the target than when it was a decoy, a difference that is significant for three of the four clips. On average, a clip was identified as the target 58% of the time when it was the target compared with only 14% of the time when it was a decoy. In other words, there is an effect over and above that pro- duced by response bias. Next, we can calculate a conservative estimate of that remaining effect by imagining a hypothetical set of in- formed receivers who were able to maximally exploit the unequal target frequencies to achieve the highest possible hit rate. Their optimal (non-psi) strategy would be to iden- Approved For Release 2000/08/10 : CIA-RDP96-00792R000100130002-1 Approved For Rele ?ftWOQWfiQRQ 000100130002-1 tify the most frequent clip (Bugs Bunny) as the target in every session;, thereby achieving a hit rate of 44%. This figure thus represents the hit rate expected if response bi- ases were making their maximum possible contribution to the hit rate-a worst case baseline for evaluating any re- maining psi effect. When the observed hit rate of 64% is compared with a hypothetical hit rate of 44%, the effect size (h) is .40. As shown in Table 1, this is equivalent to a four-alternative hit rate of (coincidentally) 44% or a is value of .70 and is statistically significant (z = 2.02, p = .022). Dynamic versus static targets. The success of Study 302 raises the question of whether dynamic targets are, in general, more effective than static targets. This possibility was also suggested by the earlier meta-analysis, which found that studies using multiple-image targets (View Master stereoscopic slide reels) obtained significantly higher hit rates than did studies using single-image tar- gets. By adding motion and sound, the video clips might be thought of as high-tech versions of the View Master reels. The ten autoganzfeld studies that randomly sampled from both dynamic and static target pools yielded an even split of 165 sessions with each target type. As predicted, sessions using dynamic targets yielded significantly more hits than did sessions using static targets (37% vs. 27%), Fisher's exact p < .04. Sender/ receiver pairing. The earlier meta-analysis found that studies in which participants were free to bring in friends to serve as senders produced significantly higher hit rates than studies that used only laboratory-as- signed senders. As noted, however, there is no record of how many of the participants in the former studies actu- ally did bring in friends. Whatever the case, sender/receiver pairing was not a significant correlate of psi performance in the auto- ganzfeld studies: The 198 sessions in which the sender and receiver. were friends did not yield a significantly higher proportion of hits than did the 132 sessions in which they were not (34% vs. 29%), Fisher's exact p = .34. Correlations between receiver characteristics and psi performance. Most of the autoganzfeld participants were strong believers in psi: On a 7-point scale, where "1" indi- cates strong disbelief and "7" indicates strong belief in psi, the mean was 6.2 (SD = 1.03); only two participants rated their belief in psi below the midpoint of the scale. In addi- tion, 88% of the participants reported personal experi- ences suggestive of psi and 80% had some training in meditation or other techniques involving internal focus of attention. All of these appear to be important variables. The corre- lation between belief in psi and psi performance is one of the most consistent findings in the parapsychological lit- erature (Palmer, 1978). And within the autoganzfeld stud- ies, successful performance of novice (first-time) partici- pants is significantly predicted by reported personal psi experiences, involvement with meditation or other mental disciplines,' and high scores on the Feeling and Perception factors of the Myers-Briggs Type Inventory (Honorton, 1992; Honorton & Schechter, 1987). This recipe for success has now been independently replicated in another laboratory (Broughton, Kanthamani, & Khilji, 1990). The personality trait of extraversion is also associated with better psi performance. A meta-analysis of 60 inde- pendent studies with nearly 3,000 subjects revealed a small but reliable positive correlation between extraver- sion and psi performance especially in studies that used free-response methods of the kind employed in the ganzfeld experiments (Honorton, Ferrari, & Bern, 1992). Across 14 free-response studies by 4 independent investi- gators, the correlation for 612 subjects was .20 (z = 4.82, p = 1.5 x 10-6). This correlation was replicated in the auto- ganzfeld studies, where extraversion scores were available for 221 of the 241 subjects: r = .18, t (219) = 2.67, p = .004, one-tailed. And finally, there is the strong psi performance of the Juilliard students, discussed above, which is consistent with other studies in the parapsychological literature suggesting a relationship between successful psi perfor- mance and creativity or artistic ability. Discussion Earlier in this article we quoted from the abstract of the Hyman-Honorton communique: "We agree that the final verdict awaits the outcome of future experiments con- ducted by a broader range of investigators and according to more stringent standards" (1986, p. 351). We believe that the "stringent standards" requirement has been met by the autoganzfeld studies. The results are statistically significant and consistent with those in the earlier database. The mean effect size is quite respectable when compared with other controversial research areas of human performance (Harris & Rosenthal, 1988a). And, there are reliable relationships between successful psi , performance and conceptually relevant experimental and subject variables-relationships that also replicate previ- ous findings. Hyman has also commented on the auto- ganzfeld studies: Honorton's experiments have produced intriguing results. If. .. independent laboratories can produce similar results with the same relationships and with the same attention to rigorous methodology, then parapsychology may indeed have finally captured its elusive quarry. (1991, p. 392) Issues of Replication As Hyman's comment implies, the autoganzfeld studies by themselves cannot satisfy the requirement that repli- cations be conducted by a "broader range of investigators." Accordingly, we hope the findings reported here will be sufficiently provocative to prompt others to try replicating the psi ganzfeld effect. We believe it is essential, however, that future studies comply with the methodological, statistical, and reporting standards set forth in the joint communique and achieved by the autoganzfeld studies. It is not necessary for studies to be as automated or as heavily instrumented as the au- toganzfeld studies in order to satisfy the methodological guidelines, but they are still likely to be labor intensive and potentially expensive .6 6As the closing of the autoganzfeld laboratory exemplifies, it is also difficult to obtain funding for psi research. The traditional, peer-refereed sources of funding familiar to psychologists have almost never funded proposals for psi research. The widespread skepticism of psychologists toward psi is almost certainly a con- tributing factor. Approved For Release 2000/08/10 : CIA-RDP96-00792R000100130002-1 Approved For Rele.sel OOtQ81 o i. ' 000100130002-1 Statistical Power and Replication Would-be replicators also need to be reminded of the power requirements for replicating small effects. Although many academic psychologists do not believe in psi, many apparently do believe in miracles when it comes to repli- cation. Tversky and Kahneman (1971) posed the following problem to their colleagues at meetings of the Mathemati- cal Psychology Group and the American Psychological As- sociation: Suppose you have run an experiment on 20 subjects and have obtained a significant result which confirms your the- ory (z = 2.23, p < .05, two-tailed). You now have cause to run an additional group of 10 subjects. What do you think the probability is that the results will be significant, by a one- tailed test, separately for this group? (p. 105) The median estimate was .85, with nine out of ten re- spondents giving an estimate greater than .60. The cor- rect answer is approximately .48. As Rosenthal (1990) has warned: "Given the levels of statistical power at which we normally operate, we have no right to expect the proportion of significant results that we typically do expect, even if in nature there is a very real and very important effect" (p. 16). In this regard, it is again instructive to consider the medical study that found a highly significant effect of as- pirin on the incidence of heart attacks. The study moni- tored over 22,000 subjects. Had the investigators moni- tored 3,000 subjects, they would have had less than an even chance of finding a conventionally significant effect. Such is life with small effect sizes. Given its larger effect size, the prospects for success- fully replicating the psi ganzfeld effect are not quite so daunting, but they are probably still grimmer than intu- ition would suggest. If the true hit rate is in fact about 34% when 25% is expected by chance, then an experiment with 30 trials (the mean for the 28 studies in the original meta-analysis) has only about 1 chance in 6 of finding an effect significant at the .05 level with a one-tailed test. A 50 trial experiment boosts that to about 1 in 3. One must escalate to 100 trials in order to come close to the break even point-where one has a 50-50 chance of finding a statistically significant effect (Utts, 1986). (Recall that only 2 of the 11 autoganzfeld studies yielded results that were individually significant at the conventional .05 level.) Those who require that a psi effect be statistically significant every time before they will seriously entertain the possibility that an effect really exists know not what they ask. Significance vs. Effect Size But the preceding discussion is unduly pessimistic be- cause it perpetuates the tradition of worshipping the sig- nificance level. Regular readers of this journal are likely to be familiar with recent arguments imploring behavioral scientists to overcome their slavish dependence on the significance level as the ultimate measure of virtue and to focus more of their attention on effect sizes instead: "Surely, God loves the .06 nearly as much as the .05" (Rosnow & Rosenthal, 1989, p. 1277). Accordingly, we suggest that achieving a respectable effect size with a methodologically tight ganzfeld study would be a perfectly welcome contribution to the replication effort-no matter how untenurable the p level renders the investigator. Career consequences aside, this suggestion may seem quite counterintuitive. Again, Tversky and Kahneman (1971) provide an elegant demonstration. They asked sev- eral of their colleagues to consider an investigator who runs 15 subjects and obtains a significant t value of 2.46. Another investigator attempts to duplicate the procedure with the same number of subjects and obtains a result in the same direction but with a nonsignificant value of t. Tversky and Kahneman then asked their colleagues to in- dicate the highest level of t in the replication study they would describe as a failure to replicate. The majority of their colleagues regarded t = 1.70 as a failure to replicate. But if the data from two such studies (t = 2.46 and t = 1.70) were pooled, the t for the combined data would be about 3.00 (assuming equal variances): Thus, we are faced with a paradoxical state of affairs, in which the same data that would increase our confidence in the finding when viewed as part of the original study, shake our confidence when viewed as an independent study. (p. 108) Such is the iron grip of the arbitrary .05. Pooling the data, of course, is what meta-analysis is all about. Ac- cordingly, we suggest that two or more laboratories could collaborate in a ganzfeld replication effort by conducting independent studies and then pooling them in meta-ana- lytic fashion-what we might call real-time meta-analy- sis. (Each investigator could then claim the pooled p level for his or her own curriculum vitae.) Maximizing Effect Size Rather than buying or borrowing larger sample sizes, those who seek to replicate the psi ganzfeld effect might find it more intellectually satisfying to attempt to maxi- mize the effect size by attending to the variables associ- ated with successful outcomes. Thus researchers who wish to enhance the chances of successful replication should use dynamic rather than static targets. Similarly we ad- vise using participants with the characteristics we have reported to be correlated with successful psi performance. Random college sophomores enrolled in introductory psy- chology do not constitute the optimal subject pool. And finally, we urge, ganzfeld researchers to read care- fully the detailed description of the warm social ambiance that Honorton et al. (1990) sought to create in the auto- ganzfeld laboratory. We believe that the social climate created in psi experiments is a critical determinant of their success or failure. The Problem of "Other" Variables This caveat about the social climate of the ganzfeld ex- periment prompted one reviewer of this article to worry that this provided "an escape clause" which weakens the falsifiability of the psi hypothesis: "Until Bern and Hon- orton can provide operational criteria for creating a warm social ambiance, the failure of an experiment with otherwise adequate power can always be dismissed as due to a lack of warmth." Alas, it's true; we devoutly wish it were otherwise. But the operation of unknown variables in moderating the success of replications is a fact of life in all the sciences. Consider, for example, an earlier article in this journal by Spence (1964). He reviewed studies testing the straightforward derivation from Hullian learning theory that high anxiety subjects should condition more Approved For Release 2000/08/10 : CIA-RDP96-00792R000100130002-1 Approved For Rele20,@W8/1pVR$JI000100130002-1 strongly than low anxiety subjects. This hypothesis was confirmed 94% of the time in Spence's own laboratory at the University of Iowa but only 63% of the time in labo- ratories at other universities. In fact, Kimble and his as- sociates at Duke and North Carolina obtained results in the opposite direction in two out of three experiments. In searching for a post hoc explanation, Spence noted that "a deliberate attempt was made in the Iowa studies to provide conditions in the laboratory that might elicit some degree of emotionality. Thus, the experimenter was instructed to be impersonal and quite formal ... and did not try to put [subjects] at ease or allay any expressed fears." Moreover, he pointed out, his subjects sat in a dental chair whereas Kimble's subjects sat in a secretar- ial chair. Spence even considered "the possibility that cultural backgrounds of southern and northern students may lead to a difference in the manner in which they re- spond to the different items in the [Manifest Anxiety] scale." If this was the state of affairs in an area of research as well established as classical conditioning, then the sug- gestion that the social climate of the psi laboratory might affect the outcome of ganzfeld experiments in ways not yet completely understood should not be dismissed as a devious attempt to provide an "escape clause" in case of replication failure. The best the! original researcher can do is provide as complete a description of the experimental conditions as possible in an attempt to anticipate what some of the relevant moderating variables might be. The detailed de- scription of the autoganzfeld procedures provided by Honorton et al. (1990) comes as close as current knowl- edge permits in providing the "operational criteria for creating a warm social ambiance." Theoretical Considerations Up to this point, we have confined our discussion to strictly empirical matters. We are sympathetic to the view that one should establish the existence of a phenomenon, anomalous or not, before attempting to explain it. So let us suppose for the moment that it's true. Let us suppose that we have a genuine anomaly of information transfer before us. How can it be understood or explained? The Psychology of Psi In attempting to understand psi, parapsychologists have typically begun with the working assumption that, whatever its underlying mechanisms, it should behave like other, more familiar psychological phenomena. In particular, they typically assume that target information behaves like an external sensory stimulus that is encoded, processed, and experienced in familiar information-pro- cessing ways. Similarly, individual psi performances should covary with experimental and subject variables in psychologically sensible ways. These assumptions are em- bodied in the model of psi that motivated the ganzfeld studies in the first place. The ganzfeld procedure. As noted in the introduction, the ganzfeld procedure was designed to test a model in which psi-mediated information is conceptualized as a weak signal that is normally masked by internal somatic and external sensory "noise." Accordingly, any technique that raises the signal-to-noise ratio should enhance a per- son's ability to detect the psi-mediated information. This noise-reduction model of psi organizes a large and diverse body of experimental results, particularly those demon- strating the psi-conducive properties of altered states of consciousness like meditation, hypnosis, dreaming, and, of course, the ganzfeld itself (Rao & Palmer, 1987). Alternative theories propose that the ganzfeld (and al- tered states) may be psi-conducive because it lowers resis- tance to accepting alien imagery, diminishes rational or contextual constraints on the encoding or reporting of in- formation, stimulates more divergent thinking, or even just serves as a placebo-like ritual that participants per- ceive as being psi conducive (Stanford, 1987). At this point, there are no data that would permit us to choose among these alternatives, and the noise-reduction model remains the most widely accepted. The target. There are also a number of plausible hy- potheses that attempt to account for the superiority of dy- namic targets over static targets: Dynamic targets contain more information, involve more sensory modalities, evoke more of the receiver's internal schemata, are more life- like, have a narrative structure, are more emotionally evocative, and are "richer" in other, unspecified ways. Several psi researchers have attempted to go beyond the simple dynamiclstatic dichotomy to more refined or the- ory-based definitions of a good target. Although these ef- forts have involved examining both psychological and physical properties of targets, there is not much progress to report yet (Delanoy, 1990). The receiver. Some of the subject characteristics asso- ciated with good psi performance also appear to have psy- chologically straightforward explanations. For example, garden-variety motivational explanations seem sufficient to account for the relatively consistent finding that those who believe in psi perform significantly better than those who do not. (Less straightforward, however, would be an explanation for the frequent finding that nonbelievers ac- tually perform significantly worse than chance (Broughton, 1991, p. 109).) The superior psi performance of creative or artistically gifted individuals-like the Juilliard students-may re- flect individual differences that parallel some of the hy- pothesized effects of the ganzfeld, mentioned above: Ar- tistically gifted individuals may be more receptive to alien imagery, be better able to transcend rational or contextual constraints on the encoding or reporting of information, or be more divergent in their thinking. It has also been sug- gested that both artistic and psi abilities might be rooted in superior right-brain functioning. The observed relationship between extraversion and psi performance has been of theoretical interest for many years. Eysenck (1966) reasoned that extraverts should perform well in psi tasks because they are easily bored and respond favorably to novel stimuli. In a setting like the ganzfeld, extraverts may become "stimulus starved" and thus be highly sensitive to any stimulation, including weak incoming psi information. In contrast, introverts would be more inclined to entertain themselves with their own thoughts and thus continue to mask psi information despite the diminished sensory input. Eysenck also specu- lated that psi might be a primitive form of perception an- tedating cortical developments in the course of evolution, and, hence, cortical arousal might suppress psi function- ing. Because extraverts have a lower level of cortical arousal than introverts, they should perform better in psi tasks. (The evolutionary biology of psi is also discussed by Broughton (1991, pp. 347-352).) Approved For Release 2000/08/10 : CIA-RDP96-00792R000100130002-1 Approved For ReIR~ft,QWQhQRF,%7jR000100130002-1 13 But there are more mundane possibilities. Extraverts might perform better than introverts simply because they are more relaxed and comfortable in the social setting of the typical psi experiment (e.g., the "warm social am- biance" of the autoganzfeld studies). This interpretation is strengthened by the observation that introverts outper- formed extraverts in a study in which subjects had no con- tact with an experimenter but worked alone at home with materials they received in the mail (Schmidt & Schlitz, 1989). In order to help decide among these interpreta- tions, ganzfeld experimenters have begun to use the ex- traversion scale of the NEO personality inventory (Costa & McCrae, 1985), which assesses six different facets of the extraversion-introversion factor. The sender. In contrast to all this information about the receiver in psi experiments, virtually nothing is known about the characteristics of a good sender or about the ef- fects of the sender's relationship to the receiver. As we have seen, the initial suggestion from the meta-analysis of the original ganzfeld database that psi performance might be enhanced when the sender and receiver are friends was not replicated at a statistically significant level in the au- toganzfeld studies. A number of parapsychologists have entertained the more radical hypothesis that the sender may not even be a necessary element in the psi process. In the terminology of parapsychology, the sender-receiver procedure tests for the existence of telepathy, anomalous communication be- tween two individuals; but if the receiver is somehow picking up the information from the target itself, it would be termed clairvoyance, and the presence of the sender would be irrelevant (except for possible psychological reasons like expectation effects). At the time of his death, Honorton was planning a se- ries of autogarizfeld studies that would systematically compare sender with no-sender conditions while keeping both the receiver and the experimenter blind to the condi- tion of the ongoing session. In preparation, he conducted a meta-analytic review of ganzfeld studies that used no sender. He found 12 studies with a median of 33.5 ses- sions conducted by 7 investigators. The overall effect size (n) was .56, which corresponds to a four-alternative hit rate of 29%. But this effect size does not reach statistical significance (Stouffer z = 1.31, p = .095). So far, then, there is no firm evidence for psi in the ganzfeld in the ab- sence of a sender. (There are, however, non-ganzfeld studies in the literature that do report significant evi- dence for clairvoyance, including a classic card-guessing experiment by Rhine (Rhine & Pratt, 1954).) The Physics of Psi The psychological level of theorizing discussed above does not, of course, address the conundrum that makes psi phenomena anomalous in the first place: their presumed incompatibility with our current conceptual model of physical reality. Parapsychologists differ widely from one another in their taste for theorizing at this level, but sev- eral whose training lies in physics or engineering have proposed physical (or biophysical) theories of psi phenom- ena. (An extensive review of theoretical parapsychology is provided by Stokes (1987).) Only some of these would force a radical :revision in our conception of physical real- ity. Those who follow contemporary debates in modern physics, however, will be aware that several phenomena predicted by quantum theory and confirmed by experi- ment are themselves incompatible with our current con- ceptual model of physical reality. Of these, it is the 1982 empirical confirmation of Bell's theorem that has created the most excitement and controversy among philosophers and the few physicists who are willing to speculate on such matters (Cushing & McMullin, 1989; Herbert, 1987). In brief, Bell's theorem states that any model of reality that is compatible with quantum mechanics must be non- local. This implies, among other things, that any model of reality compatible with quantum mechanics must allow for the possibility that information about an event at one location can be instantaneously available at some other arbitrarily distant location, unattenuated and without the mediation of any kind of transmitting signal (Herbert, 1987). Several possible models of reality that incorporate non- locality have been proposed by both philosophers and physicists. Some of these clearly rule out psi-like informa- tion transfer; others permit it; and some actually require it. Thus, at a grander level of theorizing, some parapsy- chologists believe that one of the more radical models of reality compatible with both quantum mechanics and psi will eventually come to be accepted. If and when that oc- curs, psi phenomena would cease to be anomalous. But we have learned that all such talk provokes most of our colleagues in psychology and in physics to roll their eyes and gnash their teeth. So let's just leave it at that. More generally, we have learned that our colleagues' tolerance for any kind of theorizing about psi is strongly determined by the degree to which they have been con- vinced by the data that psi has been demonstrated. We have further learned that their diverse reactions to the data themselves are strongly determined by their a priori beliefs about and attitudes toward a number of quite gen- eral issues, some scientific, some not. In fact, several statisticians believe that the traditional hypothesis test- ing methods used in the behavioral sciences should be dis- carded in favor of Bayesian analyses, which take into ac- count a person's a priori beliefs about the phenomenon under investigation (e.g., Bayarri & Berger, 1991; Daw- son, 1991). But in the final analysis, we suspect that both one's Bayesian a prioris and one's reactions to the data are ul- timately determined by whether one was more severely punished in childhood for Type I or Type II errors. 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