Meta-Analysis of Free-Response Studies 2009-2018: Assessing the Noise-Reduction Model Ten Years On

📌 Appears in:

⚡ Ganzfeld Telepathy ⚡ Bem Feeling The Future

Plain English Summary

This sweeping update covers 44 years of research asking whether people can pick up hidden information while in the ganzfeld — a relaxed, sensory-reduced state using halved ping-pong balls over your eyes and white noise in your ears. Combining over a hundred studies, ganzfeld participants identified hidden targets more often than chance, with roughly one-in-a-billion odds against a fluke. Unlike dream-ESP research, there's no sign the effect is fading — it has held steady for four decades. People pre-selected for psychic aptitude did better than unselected volunteers, and both traditional and Bayesian statistics agreed on every finding.

Actual Paper Abstract

We report the results of an update to the meta-analysis by Storm, Tressoldi, and Di Risio (2010). Three types of free-response design were assessed: (i) ganzfeld (a technique that enhances a communication anomaly referred to as 'psi'); (ii) nonganzfeld noise reduction using alleged psi-enhancing techniques (e.g., dreaming, hypnosis, relaxation, and meditation); and (iii) standard free-response (nonganzfeld; no noise reduction). These experimental (laboratory-based) designs allegedly elicit a communications anomaly known as extrasensory perception (ESP; a.k.a. psi). For the period 2009 to 2018, a dataset of nine new ganzfeld studies (Category 1) yielded a mean ES = 0.119; 19 new nonganzfeld noise-reduction studies (Category 2) yielded mean ES = 0.045; and 15 new free-response studies (Category 3) yielded mean ES = 0.050. Stouffer Z scores for all three databases were significant, but each new database was not significantly different from its respective database in Storm et al. (2010). The increased ganzfeld database (N = 38) yielded a mean ES = 0.133; the nonganzfeld noise-reduction dataset (N = 37) yielded mean ES = 0.072; and the standard free-response studies (N = 33) yielded mean ES = 0.027. Again, Stouffer Z scores were significant. We did find category differences, and participants (selected vs. unselected) performed differently, but there were no differences between modality (i.e., type of psi), types of target (e.g., film clips, photographs), or experimenter/laboratory. There was also no evidence of a decline effect across the 44-year period. Finally, we conducted a Bayesian analysis and found that the case for a communications anomaly using free-response designs was upheld.

Research Notes

The most comprehensive update to the ganzfeld free-response meta-analytic tradition, spanning 44 years and 117 ganzfeld studies. Central to the ganzfeld telepathy debate (Controversy #1), it directly extends Storm et al. (2010) and responds implicitly to critiques by Hyman and Rouder et al. The absence of decline effects and convergence to ES~0.15 are frequently cited by proponents.

An update to Storm, Tressoldi, and Di Risio (2010), this meta-analysis assessed free-response ESP studies from 2009-2018 in three categories: ganzfeld (k=9, ES=0.119), nonganzfeld noise-reduction (k=19, ES=0.045), and standard free-response (k=15, ES=0.050), all with significant Stouffer Z scores. Combined with 1992-2008 databases (total k=108), ganzfeld yielded ES=0.133 (95% CI [0.071, 0.194], p=1.37x10^-9), noise-reduction ES=0.072, and standard free-response ES=0.027. No decline effect appeared across 44 years. Ganzfeld significantly outperformed standard free-response, and selected participants outperformed unselected in ganzfeld. Bayesian analysis confirmed all classical results.