A quantitative digest of the ESP-Nexus structured study database for Free-Response ESP: 6 studies spanning 1970–2012, with every figure traceable to its source. ESP-Nexus reports what the studies found and takes no position on whether the effects are genuine.
Two meta-analyses anchor the quantitative picture. Milton (1997) pooled 78 free-response studies and found a mean effect size of 0.16 (z/√n), while Storm (2010) pooled 29 studies from 1992 to 2008 and obtained a mean of 0.142 (z/√n). Both are small but positive, suggesting a consistent above-chance signal across many laboratories. Individual studies show wider variation. Tressoldi (2021) reported a notably larger Pearson r of 0.81, which sits far above the meta-analytic averages and raises questions about sample size, selection, or methodological differences. Rock (2012) and Baptista (2014) each returned effect sizes close to the meta-analytic center, while Roe (2006) and Watt (2002) reached conventional significance thresholds.
Null and mixed results also appear in the literature, and the spread of effect sizes across studies signals meaningful heterogeneity. The Morris (2001) study recorded a hit rate of 0.40 without a clear benchmark provided in this evidence set, making direct interpretation uncertain. The overall pattern is a small pooled positive effect that persists across independent analyses, but substantial variability between studies prevents any straightforward consensus on magnitude or replicability.
Pooled meta-analytic effects
- Storm (2010), Psychological Bulletin: ES 0.142 (z_over_sqrt_n) (k = 29)
- Milton (1997), The Journal of Parapsychology: ES 0.16 (z_over_sqrt_n) (k = 78)
The evidence
| Paper | Reported finding | Effect / significance | Basis |
|---|---|---|---|
| Rock et al. (2012), International Journal of Transpersonal Studies [source] | Combined shamanic-like group, N=107. | ES 0.13, hit rate 0.308 | N = 107 |
| Storm et al. (2010), Psychological Bulletin [source] | Category 1 – homogeneous 29-study set. | ES 0.142, z = 5.48, p = 2.1 × 10−8, hit rate 0.322 | 29 studies; N = 1498 |
| Watt et al. (2002), Journal of Parapsychology | Overall belief-syllogisms Pearson correlation. | ES -0.28, p = .03 | N = 59 |
| Milton (1997), The Journal of Parapsychology | Overall cumulation – all 78 nonASC free-response studies. | ES 0.16, z = 5.72, p < 5.4 × 10−9 | 78 studies; N = 2682 |
| Greyson (1977), The Journal of Nervous and Mental Disease | Free-response ESP performance of 9 completing claimant patients. | — | N = 45 |
| Moss (1970), Conference on Methodology in Psi Research (proceedings/transcript) | Pilot study – judge-matched protocols. | p = .001 | N = 26 |
What is unsettled
- Reported directions disagree across studies (some positive, some null or below-chance).
- 1 result(s) report a null or below-chance (negative) effect.
Source: ESP-Nexus structured study database, 6 studies. 6 born-digital figures; OCR-derived figures awaiting source-verification are excluded from this digest. Effect sizes are shown only where a standardized metric is recorded.