Feeling the Future: A Meta-Analysis of 90 Experiments on the Anomalous Anticipation of Random Future Events
Patrizio E. Tressoldi
Università di Padova
University of Nantes
Nottingham Trent University
April 11, 2014
In 2011, the Journal of Personality and Social Psychology published a report of nine experiments purporting to demonstrate that an individual’s cognitive and affective responses can be influenced by randomly selected stimulus events that do not occur until after his or her responses have already been made and recorded, a generalized variant of the phenomenon traditionally denoted by the term precognition (Bem, 2011). To encourage replications, all materials needed to conduct them were made available on request. We here report a meta-analysis of 90 experiments from 33 laboratories in 14 countries which yielded an overall effect greater than 6 sigma, z = 6.40, p = 1.2 × 10-10 with an effect size (Hedges’ g) of 0.09. A Bayesian analysis yielded a Bayes Factor of 1.4 × 10^9, greatly exceeding the criterion value of 100 for “decisive evidence” in support of the experimental hypothesis (Jeffries, 1961). The number of potentially unretrieved experiments required to reduce the overall effect size to a trivial value is 547. Several tests demonstrate that the database is not significantly compromised by publication bias, selection bias, or by “p-hacking,” the selective suppression of findings or statistical analyses that failed to yield statistical significance. An analysis of p–curve, the distribution of significant p values (Simonsohn, Nelson, & Simmons, 2014a; 2014b) estimates the true effect size of the database to be 0.20, virtually identical to the effect size of Bem’s original studies (0.22). We discuss the controversial status of precognition and other anomalous effects collectively known as psi.
Number of Pages in PDF File: 58
Keywords: precognition, psi, ESP, retrocausation, retro-priming, parapsychology
Date posted: April 12, 2014 ; Last revised: February 8, 2015
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