Meta-Analysis of Free-Response ESP Studies Without Altered States of Consciousness
📄 Original study📌 Appears in:
Plain English Summary
Can people pick up information through ESP when they're in a perfectly normal, everyday state of mind? This landmark meta-analysis (a study that combines results from many studies) gathered 78 experiments spanning nearly three decades, covering 2,682 trials with over a thousand participants. The overall result was statistically significant -- you'd need 866 unpublished negative studies hiding in file drawers to make it disappear, which is a lot. Impressively, study quality didn't correlate with effect size, meaning better-run experiments weren't less likely to find results. Telepathy and precognition (sensing future events) showed real effects, though clairvoyance didn't. Here's the big catch: a whopping 96% of studies failed to report whether they'd decided in advance what they were measuring, raising a serious red flag about possible cherry-picking of results. This tension between genuinely robust statistics and worrying methodological gaps set the stage for the heated ganzfeld telepathy debate that followed.
Actual Paper Abstract
Seventy-eight free-response ESP studies in which participants were not in an altered state of consciousness were meta-analyzed, There was a highly significant cumulative effect (Stouffer z= 5.72, p < 5.4.x 10°, one-tailed), The mean effect size (Nn 5 was 0.16 (SD = 0.29). Crude selective reporting appears to be an implausible counterexplanation of the overall cumulation and there were no strong positive indications that methodological artifacts played a role in producing above-chance results. However, the failure to report that the outcome measure was preplanned in 96% of the studies and the frequent use of multiple measures raises the possibility of widespread post hoc data selection problems within the studies themselves. No data are available to resolve the question of whether this threat to the database's validity is merely potential. Because of this problem and the obstacles to obtaining statistical evidence of the effects of flaws in any meta-analysis, caution is recommended in drawing strong conclusions from this meta-analysis about the existence of a genuine anomaly. However, a number of possible moderator variables were identified that suggest directions for future research,
Research Notes
The foundational non-ganzfeld free-response ESP meta-analysis, preceding Milton & Wiseman’s (1999) ganzfeld replication attempt. Its careful assessment of 18 methodological safeguards and the concern about outcome prespecification (96% unreported) set the methodological standard for the ganzfeld debate. Central to Controversy #1 (Ganzfeld Telepathy).
Seventy-eight free-response ESP studies (1964–1992) not involving altered states of consciousness were meta-analyzed across 2,682 trials and 1,158 receivers. The overall mean effect size was 0.16 (SD = 0.29, Stouffer Z = 5.72, p < 5.4 × 10⁻⁹). A homogeneous 75-study subset confirmed the result (ES = 0.17, Z = 5.85). File-drawer analysis required 866 null studies to nullify significance. Quality-weighted analyses showed significant telepathy and precognition but not clairvoyance. No correlation between total flaws and effect size was found, though 96% of studies failed to report prespecified outcome measures, raising concerns about post hoc data selection. Three moderators survived Bonferroni correction: target type, judging set size, and judge identity.
Related Papers
Precursor
Cites
- Does Psi Exist? Replicable Evidence for an Anomalous Process of Information Transfer — Bem, Daryl J (1994)
- Information transmission under conditions of sensory shielding — Targ, Russell (1974)
- The "File Drawer Problem" and Tolerance for Null Results — Rosenthal, Robert (1979)
- An Evaluation of Remote Viewing: Research and Applications — Mumford, Michael D (1995)
Extended By
- Does Psi Exist? Lack of Replication of an Anomalous Process of Information Transfer — Milton, Julie (1999)
- Does Psi Exist? Comments on Milton and Wiseman's (1999) Meta-Analysis of Ganzfeld Research — Storm, Lance (2001)
- Meta-Analysis of Free-Response Studies, 1992–2008: Assessing the Noise Reduction Model in Parapsychology — Storm, Lance (2010)
- Meta-Analysis of Free-Response Studies 2009-2018: Assessing the Noise-Reduction Model Ten Years On — Storm, Lance (2020)
Also by these authors
More in Telepathy
Telecommunication Telepathy: A Meta-Analysis
Rethinking Communication and Consciousness: Lessons from The Telepathy Tapes Podcast
Taking the Mindfield Literally: Discovering Minds by Assuming Competence Among Nonspeakers
Who's Calling? Evaluating the Accuracy of Guessing Who Is on the Phone
A Comparison of Four New Automated Telephone Telepathy Tests
📋 Cite this paper
Milton, Julie (1997). Meta-Analysis of Free-Response ESP Studies Without Altered States of Consciousness. Journal of Parapsychology.
@article{milton_1997_free_response,
title = {Meta-Analysis of Free-Response ESP Studies Without Altered States of Consciousness},
author = {Milton, Julie},
year = {1997},
journal = {Journal of Parapsychology},
}