Carlos S. Alvarado, Ph.D., Visiting Scholar, Rhine Research Center
Those of you interested in the cumulative experimental databases of parapsychology are probably aware of the various meta-analyses that have been published over the years. In her article “Replication and Meta-Analysis in Parapsychology” (Statistical Science, 1991, 6, 363-403 http://www.ics.uci.edu/~jutts/UttsStatPsi.pdf) statistician Jessica Utts reviewed the use of meta-analysis in parapsychology concluding that:
“The recent focus on meta-analysis in parapsychology has revealed that there are small but consistently nonzero effects across studies, experimenters and laboratories . . . It may be that the nonzero effects observed in the meta-analyses can be explained by something other than ESP . . . Nonetheless, there is an anomaly that needs an explanation.”
In recent years other meta-analyses have appeared that support this conclusion. Three examples follow.
Schmidt, S. (2012). Can we help just by good intentions? A meta-analysis of experiments on distant intention effects. Journal of Alternative and Complementary Medicine,18, 529-533. http://online.liebertpub.com/doi/pdfplus/10.1089/acm.2011.0321
OBJECTIVES: In recent years, several clinical trials have assessed effects of distant healing. The basic question raised by these studies is whether a positive distant intention can be related to some outcome in a target person. There is a specific simple experimental setup that tests such a basic assumption. The task is to focus attention and to indicate unwanted mind wandering by a button press while at the same time a second remote person is either supporting this performance or not according to a randomized schedule. A meta-analysis was conducted to assess the overall effect of this experimental approach. METHODS: A systematic literature search yielded 11 eligible studies, with 576 single sessions and almost identical design, that were conducted on three different continents. Study parameters were extracted and combined with a random-effects model. RESULTS: The model yielded an overall effect size of d=0.11 (p=0.03). Furthermore, there was a significant difference of the frequency of button presses between studies conducted in Indonesia and the Western hemisphere (p<0.001). Two (2) similar experimental setups applying electrodermal activity as dependent variable meta-analyzed earlier showed almost identical effect sizes. This can be considered as mutual validation of the three data sets. CONCLUSIONS: The hypothesis of the positive effect of benevolent intentions is supported by the data presented. It is concluded that especially the intentional aspect common to all three different tasks may be responsible for these unorthodox findings. These finding may have implications for distant healing research and health care as well as for meditation performance.
Storm, L., Tressoldi, P.E., & Di Risio, L. (2012). Meta-Analysis of ESP studies, 1987-2010: Assessing the success of the forced-choice design in parapsychology. Journal of Parapsychology, 76, 243-274. http://www.psy.unipd.it/~tressold/cmssimple/uploads/includes/storm_fcesp3_jp.pdf
We report the results of a meta-analysis on forced-choice ESP studies which used targets such as card symbols, numbers, letters, and so forth. For the period 1987 to 2010, a homogeneous dataset of 72 forced-choice studies yielded a weak but significant mean effect size (ES) of 0.01 (Stouffer Z = 4.86, p = 5.90 × 10-7). There was no evidence that these results were due to low-quality design or selective reporting. The clairvoyance studies did not produce a significantly higher mean ES than the precognition studies, and target type did not make a difference to effect size. We note that effects do not vary between investigators, but we did find suggestive evidence that the number of choices per trial is inversely related to the p value. We also found evidence of a linear incline in ES values indicating that effect sizes have increased over the period 1987 to 2010. Suggestions are made that might help facilitate further increases in effect sizes.
Mossbridge, J., Tressoldi, P., & Utts, J. (2012). Predictive physiological anticipation preceding seemingly unpredictable stimuli: A meta-analysis. Frontiers of Psychology, 3, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3478568/pdf/fpsyg-03-00390.pdf
This meta-analysis of 26 reports published between 1978 and 2010 tests an unusual hypothesis: for stimuli of two or more types that are presented in an order designed to be unpredictable and that produce different post-stimulus physiological activity, the direction of pre-stimulus physiological activity reflects the direction of post-stimulus physiological activity, resulting in an unexplained anticipatory effect. The reports we examined used one of two paradigms: (1) randomly ordered presentations of arousing vs. neutral stimuli, or (2) guessing tasks with feedback (correct vs. incorrect). Dependent variables included: electrodermal activity, heart rate, blood volume, pupil dilation, electroencephalographic activity, and blood oxygenation level dependent (BOLD) activity. To avoid including data hand-picked from multiple different analyses, no post hoc experiments were considered. The results reveal a significant overall effect with a small effect size [fixed effect: overall ES = 0.21, 95% CI = 0.15–0.27, z = 6.9, p < 2.7 × 10−12; random effects: overall (weighted) ES = 0.21, 95% CI = 0.13–0.29, z = 5.3, p < 5.7 × 10−8]. Higher quality experiments produced a quantitatively larger effect size and a greater level of significance than lower quality studies. The number of contrary unpublished reports that would be necessary to reduce the level of significance to chance (p > 0.05) was conservatively calculated to be 87 reports. We explore alternative explanations and examine the potential linkage between this unexplained anticipatory activity and other results demonstrating meaningful pre-stimulus activity preceding behaviorally relevant events. We conclude that to further examine this currently unexplained anticipatory activity, multiple replications arising from different laboratories using the same methods are necessary. The cause of this anticipatory activity, which undoubtedly lies within the realm of natural physical processes (as opposed to supernatural or paranormal ones), remains to be determined.