Meta-Analysis of Free-Response ESP Studies Without Altered States of Consciousness
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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 The overall result was statistically significant -- you'd need 866 unpublished negative studies hiding in file drawers to make it disappear, which is a lot.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.
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
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A Comparison of Four New Automated Telephone Telepathy Tests
Detecting Telepathy: A Meta-Analysis for Extrasensory Perception Experiments in Last 20 Years
📋 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},
}