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Plain English Summary
When Daryl Bem claimed people can sense the future, it sparked a firestorm. This study responds with a fresh tool — a "meta-analytic Bayes factor" pooling evidence across experiments. The method has since become standard in psychology, a big deal on its own. Reanalyzing Bem's nine experiments by image type, evidence for precognition with erotic images was weak, with neutral images basically zero, but with emotional non-erotic images it hit 40 to 1 in favor. The paper also showed an earlier skeptical critique underestimated cumulative evidence. The authors land in an unusual spot: that critique was technically flawed, but they still reject ESP — 40-to-1 odds aren't enough given how implausible psychic powers are without any physical mechanism.
Research Notes
Methodologically important for introducing the meta-analytic JZS Bayes factor, now widely adopted in psychology. Occupies a distinctive middle position in the Bem debate: critiques Wagenmakers et al.'s approach as inadequate while still concluding against ESP. Central to Controversy #2.
Bayesian meta-analysis of the nine experiments in Bem's (2011) 'Feeling the Future' paper, using a newly developed meta-analytic extension of the JZS default Bayes factor t-test. Excluding three retroactive mere-exposure experiments as uninterpretable, the remaining data were categorized by stimulus type. Evidence for ESP with erotic stimuli was slight (BF = 3.23), with neutral stimuli negligible (BF = 1.57), but with emotionally valenced nonerotic stimuli noteworthy (BF = 38.7). The analysis also demonstrated that simply multiplying individual Bayes factors across experiments — as Wagenmakers et al. (2011) implicitly did — systematically underestimates cumulative evidence. Despite the BF of ~40 for emotional stimuli, the authors argued this is insufficient to overcome appropriate prior skepticism about ESP given the absence of plausible physical mechanisms.
Links
Related Papers
Cites
- Feeling the Future: Experimental Evidence for Anomalous Retroactive Influences on Cognition and Affect — Bem, Daryl J (2011)
- Why Psychologists Must Change the Way They Analyze Their Data: The Case of Psi — Wagenmakers, Eric-Jan (2011)
- Meta-Analysis of Free-Response Studies, 1992–2008: Assessing the Noise Reduction Model in Parapsychology — Storm, Lance (2010)
Cited By
- Results from a Confirmatory Replication Study of Bem (2011): Precognitive Detection of Erotic Stimuli? — Wagenmakers, Eric-Jan (2012)
- Paranormal psychic believers and skeptics: a large-scale test of the cognitive differences hypothesis — Gray, Stephen J (2016)
- Must Psychologists Change the Way They Analyze Their Data? — Bem, Daryl J (2011)
Meta Analyzes
Same Research Program
Companion
- Correcting the Past: Failures to Replicate Psi — Galak, Jeff (2012)
- Failing the Future: Three Unsuccessful Attempts to Replicate Bem's 'Retroactive Facilitation of Recall' Effect — Ritchie, Stuart J (2012)
- Too Good to Be True: Publication Bias in Two Prominent Studies from Experimental Psychology — Francis, Gregory (2012)
- Fearing the Future of Empirical Psychology: Bem's (2011) Evidence of Psi as a Case Study of Deficiencies in Modal Research Practice — LeBel, Etienne P (2011)
- Back from the Future: Parapsychology and the Bem Affair — Alcock, James E (2011)
- A Practical Solution to the Pervasive Problems of p Values — Wagenmakers, Eric-Jan (2007)
- The Garden of Forking Paths: Why Multiple Comparisons Can Be a Problem, Even When There Is No "Fishing Expedition" or "P-Hacking" and the Research Hypothesis Was Posited Ahead of Time — Gelman, Andrew (2013)
- Bem's 'Feeling the Future' (2011) Five Years Later: Its Impact on Scientific Literature — Silva, Bruno A (2017)
More in Skeptical
Cognitive Styles and Psi: Psi Researchers Are More Similar to Skeptics Than to Lay Believers
Searching for the Impossible: Parapsychology's Elusive Quest
False-Positive Effect in the Radin Double-Slit Experiment on Observer Consciousness as Determined with the Advanced Meta-Experimental Protocol
Cross-Examining the Case for Precognition: Comment on Mossbridge and Radin (2018)
N,N-Dimethyltryptamine and the Pineal Gland: Separating Fact from Myth
📋 Cite this paper
Rouder, Jeffrey N, Morey, Richard D (2011). A Bayes Factor Meta-Analysis of Bem's ESP Claim. Psychonomic Bulletin & Review. https://doi.org/10.3758/s13423-011-0088-7
@article{rouder_morey_2011_bayes_factor_bem,
title = {A Bayes Factor Meta-Analysis of Bem's ESP Claim},
author = {Rouder, Jeffrey N and Morey, Richard D},
year = {2011},
journal = {Psychonomic Bulletin & Review},
doi = {10.3758/s13423-011-0088-7},
}