Discovery Lab Answers

Patrizio E. Tressoldi, PhD is one of parapsychology’s most active meta-analysts and experimental researchers, based at the University of Padova’s Science of Consciousness Research Group (Studium Patavinum). His work spans forced-choice ESP, remote viewing, ganzfeld, mediumship, telephone telepathy, mind-matter interaction, and out-of-body experience research. The sections below work through his experiments, methodology, data, and the critical literature the sources address.

Experiments

Tressoldi’s experimental and meta-analytic record is broad. The sources retrieved for this question document several distinct lines:

Forced-choice ESP and decline effects. With Lance Storm, Tressoldi conducted a meta-analytic investigation of whether psi effects decline over time across different experimental protocols — forced-choice ESP, remote viewing, ganzfeld, and dream-ESP ^[4]. The study directly tests the “decline effect” hypothesis as applied to parapsychology databases.

Telephone / telecommunication telepathy. Tressoldi co-authored two studies in this area. With Tom Stedall, he ran an independent replication of a telephone telepathy test in which participants guessed which of two people was calling them ^[3]. He also collaborated with Rupert Sheldrake and Stedall on a broader meta-analysis pooling 26 telecommunication telepathy experiments published between 2003 and 2024 ^[2].

Remote viewing guidelines. With Jimmy Akin and Debra Lynne Katz, Tressoldi contributed to a study synthesizing expert guidelines for remote viewing protocols, examining design questions such as target selection, judging procedures, and the stacking effect ^[1].

Mediumship accuracy. The ESP-Nexus page for Tressoldi documents a large mediumship study — 100 readings under a triple-blind protocol, registered as a two-stage registered report — as one of his primary experimental contributions, though the detailed data from that study are not in the passages retrieved here.

Meta-analytic syntheses of anomalous perception. Across multiple publications, Tressoldi has conducted or co-conducted meta-analyses covering forced-choice ESP (1987–2022), ganzfeld experiments, and remote viewing, synthesizing effect sizes and testing for consistency across paradigms. The ESP-Nexus page on his meta-analytic work indicates collaboration with Storm on several of these.

Methodology

Several methodological commitments run across Tressoldi’s work:

Pre-registration. Tressoldi has consistently advocated for and used pre-registered protocols, including two-stage registered reports (Stage 1 before data collection, Stage 2 presenting results against pre-specified criteria). His mediumship study used this format, and his mind-matter interaction work — preregistered proof-of-concept studies with random number generators — follows the same principle.

Blinding. In mediumship research, Tressoldi’s triple-blind design prevented mediums, sitters, and analysts from having access to identifying information. The use of first names only in target materials was intended to prevent internet-based inference.

Meta-analytic rigor. In collaborative meta-analyses, Tressoldi and co-authors code studies for multiple variables (authors, year, device type, experimental conditions) and apply random-effects models to estimate overall effect sizes while accounting for heterogeneity. In the telecommunication telepathy meta-analysis, two coders (Tressoldi and Stedall) independently coded variables for insertion into the database ^[2].

Cognitive strategy coding. In the telephone telepathy replication, participants were asked to describe their guessing strategy, allowing post-hoc comparison between Type 1 (analytic/rational) and Type 2 (intuitive) approaches ^[3] — a design feature that generates secondary hypotheses about moderating variables.

Comparison across paradigms. In the telecommunication telepathy meta-analysis, hit rates from telephone telepathy experiments were benchmarked against ganzfeld, remote viewing, and dream-telepathy experiments to permit cross-paradigm comparison ^[2].

Data

The sources retrieved here carry statistical results for specific studies. Below is a summary of what the passages support:

A few points the data require noting:

• The primary hypothesis in the Stedall & Tressoldi replication — that hits would reach at least 55% — was not confirmed on the full sample ^[3]. The positive result emerged only in the Type 2 (intuitive strategy) subgroup, which is a secondary, post-hoc finding.
• The psi-missing result in Type 1 strategy participants (hits falling significantly below chance) is a notable anomalous pattern in the opposite direction ^[3], not merely a null.
• The meta-analytic result in Sheldrake, Stedall & Tressoldi is strongly significant overall, but selected participants had significantly higher hit rates than unselected participants ^[2], and the precognitive-condition trials produced chance-level results — a pattern the authors treat as evidence of specificity.
• On the decline effect, Tressoldi and Storm found no statistically significant decline slope across protocols, with the dream-ESP non-Maimonides subset showing a near-zero negative slope that did not approach significance ^[4].

The ESP-Nexus meta-analytic page notes a forced-choice ESP effect size of 0.02 over 1987–2022 (small but significant), a remote viewing average effect size of 0.34 across 36 studies (the strongest among paradigms compared), and ganzfeld and mediumship results above chance — but the retrieved passages do not contain the full numerical detail behind those figures, so they are not reproduced in the table above.

Skeptical critiques

What critics argue. In the telephone telepathy replication, the authors themselves record a potential confound: some callers guessed which person was calling rather than which person was being called, introducing a systematic bias. When trials involving this guess were removed, the hit rate in the remaining data was 56.3% against an effective chance expectation of 50% (p =.02) ^[3]. The stacking effect — the possibility that multiple back-to-back trials by the same participant inflate apparent significance — is acknowledged as a published concern in forced-choice designs (Thouless & Brier, 1970), with Katz noting in the remote viewing guidelines paper that the authors who first introduced the concept later concluded it was less relevant to the kinds of multi-trial remote viewing projects under discussion ^[1].

What the experimental data show. The primary hypothesis in the Stedall & Tressoldi replication (≥55% hits across all participants) was not confirmed ^[3]. The significant positive result is confined to a post-hoc subgroup defined by cognitive strategy, which the authors acknowledge is a secondary analysis. In the telecommunication telepathy meta-analysis, the precognitive-condition experiments — which share the same general design but differ on timing — produced chance-level results, providing an internal control comparison ^[2].

Analysis. The main unresolved questions the sources surface are: (1) whether the Type 2 cognitive-strategy finding in the telephone telepathy replication ^[3] is replicable under pre-specified conditions, given that it emerged from a subgroup analysis after the primary hypothesis failed; (2) whether the large meta-analytic effect in telecommunication telepathy ^[2] is stable under independent replication by groups with no prior involvement in the original experimental series — Sheldrake and colleagues conducted most of the included studies; and (3) for the decline-effect analysis, whether combining Maimonides and post-Maimonides dream-ESP databases is methodologically appropriate given Tressoldi and Storm themselves analyze them separately in part ^[4]. The sources do not include a published external critique of Tressoldi’s work by a named skeptical author, so that dimension of the critical literature is not represented here.

For a fuller overview, Tressoldi’s ESP-Nexus profile at Patrizio E. Tressoldi, PhD includes spoke pages on mediumship, remote viewing, mind-matter interaction, and his broader meta-analytic program.