ed ~ coe ani Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2 ABSTRACT We report a meta-analysis of forced-choice precognition experiments published in English-language parapsychology journals between 1935 and 1987. These studies involve attempts by subjects to predict the identity or order of target stimuli selected randomly over intervals ranging from several hundred milliseconds to one year following the subject’s responses. The database includes 309 studies reported by 62 senior authors. Nearly 2 million individual trials were contributed by more than 50,000 subjects. Study outcomes are assessed in terms of overall level of statistical significance and effect size. We find a small, but consistent, and highly significant overall tendency for directional hitting (z = 12,14). Analysis based on investigators’ predictions of conditions associated with hitting and missing yields a much stronger result (z = 24.23). Thirty percent of the studies (and 39% of the investigators) have directional outcomes that are significant at the 5% significance level. Assessment of the vulnerability of this database to selective reporting of positive results indicates that a ratio of 50 unreported studies averaging null results would be required for each reported study in order to reduce the overall significance of the observed outcomes to nonsignificance. . No systematic relationship exists between study outcomes and eight indices of research quality. Magnitude of effect has remained essentially constant over the survey period, while research quality has improved substantially. Four moderating variables appear to covary significantly with study outcome: @ Studies using subjects selected on the basis of prior testing performance show significantly larger effects than studies involving unselected sub- jects. @ Subjects tested individually by an experimenter show significantly larger effects than those tested in groups. @ Studies in which subjects are given trial-by-trial or run-score feedback have significantly larger effects than those with limited or no subject feedback. @ Studies with brief intervals between subjects’ responses and target generation show significantly stronger effects than studies involving longer intervals. The combined impact of these moderating variables appears to be very strong. A nearly perfect replication rate is observed in the subset of studies using selected subjects, who are tested individually and receive trial-by-trial feedback. Psychophysical Research Laboratories Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2
L  anenammaaee] omonasiailt aeceeien eee | einen ANDi aie | 0/08/0 -RDP96-00789R002200410001-2 Approved MRSERSE of PorcedChi Ke recognition Experiments OBJECTIVES Precognition refers to the noninferential prediction of future events. Anecdotal claims of “future knowing” have occurred throughout human history, in virtually every culture and period. Today, such claims are generally believed to be based on factors such as delusion, irrationality, and superstitious thinking. The concept of precognition runs counter to accepted notions of causality and appears to conflict with current scientific theory. Nevertheless, over the past half-century, a substantial number of experiments have been reported by more than 60 investigators claiming empirical support for the hypothesis of precognition. Subjects in forced-choice experiments, according to many reports, have correctly predicted to a statistically significant degree the identity (or order) of target stimuli randomly selected at a later time. We performed a meta-analysis of forced-choice precognition experiments published in the English-language research literature between 1935 and 1987. Five major questions were addressed through this meta-analysis: @ Is there overall evidence for accurate target identification (above chance hitting) in experimental precognition studies? @ Is there overall evidence that investigators can accurately predict tendencies toward hitting and missing? @ What is the magnitude of the overall (directional and predicted) precognition effect? @ Is the observed effect related to variations in methodologi- cal quality that could allow a more conventional explanation? @ Does precognition performance vary systematically with potential moderating variables, such as differences in sub- ject populations, stimulus conditions, experimental setting, knowledge of results, and time interval between subject response and target generation? Psychophysical Research Laboratories Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2
ns i i Reina 108 ; CIA-RDP96-00789R002200410001-2 Approved Fass analysis ol Forced hoice Precognition Experiments 3 DELINEATING THE DOMAIN Source of Studies Parapsychological research is still academically taboo and it is unlikely that there have been many dissertations and theses in this area that have escaped publication. Our retrieval of studies for this meta-analysis is therefore based on the published literature. The studies include all forced-choice precognition experiments appearing in the peer-reviewed English-language parapsychology journals: Journal of Parapsychology, Journal (and Proceedings) of the Society for Psychical Research, Journal of the American Society for Psychical Research, European Journal of Parapsychology (including the Research Letter of the Utrecht University Parapsychology Laboratory), and Research in Parapsychology. Criteria for Inclusion Our review is restricted to fixed length studies in which significance levels and effect sizes based on direct hitting can be calculated. Studies using outcome variables other than direct hitting, such as run-score variance and displacement effects, are included only if the report provides relevant information on direct hits (i.e., number of trials, hits, and probability of a hit). Finally, we exclude studies conducted by two investigators, S. G. Soal and Walter J. Levy, whose work has been unreliable. Many published reports contain more than one experiment or experimental unit. Experiments involving multiple conditions are treated as separate study units. Outcome Measures Significance Levels: We calculated two significance estimates for each study. The directionalz-score (zdir) measures the subjects’ success in scoring in the direction of their intention. The predictedz-score (Zpred) measures the investigator’s success in predicting the relative strength or direction of the outcome through conditional comparisons, experimental manipulations, or correlations; above chance scoring (hitting) is assumed in single condition experiments unless psi-missing is explicitly predicted. Predicted z’s have Psychophysical Research Laboratories Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2