Assessing 36 Years of the Forced Choice Design in Extra Sensory Perception Research: A Meta-Analysis, 1987 to 2022

Abstract

This meta-analysis is an update of Storm, Tressoldi, and Di Risio (2012); a meta-analysis on forced-choice ESP studies (1987 to 2010), which use targets such as card symbols, pictures, and letters. We formed two datasets: New Studies #1 (studies that included actual hit rates) and New Studies #2 (Reaction Time [‘RT’] Studies; which are studies that measured only reaction time, not hits, as indicators of psi responses). New Studies #1: For the period 2011 to 2022, a homogeneous dataset of 38 studies yielded a mean effect size (ES) of 0.02 (Stouffer Z = 5.55, p = 1.43 × 10–8). New Studies #2 (‘RT’ Studies): For the same period, a homogeneous dataset of 23 studies yielded a weaker mean ES of 0.01 (Stouffer Z = 5.50, p = 1.90 × 10–8). The two databases were combined. In this dataset, telepathy, clairvoyance, and precognition studies were not significantly different from each other. Nor were target types. We updated the forced-choice database by combining our revised original database with the new studies to form a homogeneous database (N = 141): mean effect size (ES) of 0.02 (Stouffer Z = 8.52, p < 10-16). Effects did not vary between investigators or laboratories, and we found a near-significant incline in ES values over a 36-year period (i.e., no evidence of a decline). These results confirm that the forced-choice design adequately tests extra-sensory perception (ESP). We compare the overall results with those obtained in other domains, focusing on ‘selected’ participants (meditators, psychics, psi-test experienced) and ‘unselected’ (i.e., untrained, naïve) participants.