TTT yy TT Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2 Meta-analysis of Forced-Choice Precognition Experiments 26 — Influence of Moderating Variables In Combination The above analyses examine the impact of each moderating variable in isolation. In this final set of analyses, we explore their joint influence on precognition performance. For this purpose, we identify two subgroups of studies. One subgroup is characterized by the use of selected subjects tested individually with trial-by-trial feedback. We refer to this as the Optimal group (N = 8 studies). The second group is characterized by the use of unselected subjects tested in groups with no feedback. We refer to this as the Suboptimal group (N = 9 studies). The Optimal studies are contributed by 4 independent investigators and the Suboptimal studies are contributed by 2 of same 4 investigators. All of the Optimal studies involve short precognitive time intervals (interval 1) while the Suboptimal studies involve longer intervals (intervals 5 and 6). All of the Optimal studies and 5 of the 9 Suboptimal studies use RNG methodology. The two groups do not differ significantly in average sample size. The mean study quality for the Optimal group is significantly higher than that of the Suboptimal studies (Optimal mean = 6.63, sd = 0.92; Suboptimal mean = 3.44, sd = 0.53; t = 8.63, 10 df, p = 3.3 x 10°, 2-tailed), The combined impact of the moderating variables appears to be quite strong: 7 of the 8 Optimal studies (87.5%) are independently significant at the 5% level, while none of the Suboptimal studies are statistically significant. All four investigators contributing studies to the Optimal group have significant outcomes, The mean z-score for the Optimal group is 2.17 (sd = 0.55) and for the Suboptimal group the mean z is -0.37 (sd = 1.05). The difference is highly significant (¢ = 6.13, 12 df, p = 2x 10°). The Optimal studies are also significantly less variable (F(7,8) = 3.67, p = .046). In terms of effect sizes, the Optimal group is 9 times larger than the Suboptimal group (mean ES = 0.055, sd = 0.045 for the Optimal studies, and 0.006, sd = 0.033) for the Suboptimal studies; this difference is also significant (¢ = 2.60, 15df,p = .01). These findings suggest that future studies combining these moderators should yield especially promising outcomes. Psychophysical Research Laboratories Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2
Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2 Meta-analysis of Forced-Choice Precognition Experiments 27 DISCUSSION Our meta-analysis of forced-choice precognition experiments confirms the existence of a small but statistically highly significant precognition effect. Most importantly, the effect appears to be replicable; significant confirmations are reported by two dozen investigators using a variety of methodological paradigms and subject populations. Estimates of the “filedrawer” problem and consideration of parapsychological publication practices indicate that the precognition effect cannot be plausibly explained on the basis of selective publication bias. Analyses of precognitive effect sizes in relation to eight measures of research quality fail to support the hypothesis that the observed effect is driven to any appreciable extent by methodological artifacts; indeed, several of the analyses indicate that methodologically superior studies yield stronger effects than methodologically weaker studies. Analyses of parapsychological alternatives to precognition, although limited to the subset of studies using random number tables, provide no support for the hypothesis that the effect results from the operation of contemporaneous ESP and PK at the time of randomization. The most important outcome of the meta-analysis is the identification of several moderating variables that appear to covary systematically with precognition performance. The largest effects are observed in studies using subjects selected on the basis of prior test performance, who are tested individually, and receive trial-by-trial feedback. The outcomes of studies combining these factors contrast sharply with the null outcomes associated with the combination of group testing, unselected subjects, and no feedback of results. The identification of these moderating variables has important implications for our understanding of the phenomena and provides a clear direction for future research. The existence of moderating variables indicates that the precognition effect is not merely an unexplained departure from a theoretical chance baseline, but is rather an effect that covaries with factors known to influence more familiar aspects of human performance. It should now be possible to exploit these moderating factors to increase the magnitude and reliability of precognition effects in new studies. Psychophysical Research Laboratories Approved For Release 2000/08/08 : CIA-RDP96-00789R002200410001-2