Discovery Lab Answers

Has the PK effect size increased over the last 50 years?

The short answer: the retrieved ESP-Nexus material does not support a claim that psychokinesis (PK) effect sizes have increased — if anything, the documented pattern points the other way, toward small, contested effects and prominent replication difficulties. None of the numbered primary sources retrieved here contains a longitudinal effect-size trend for PK, so I can’t give you a quantified “then vs. now” figure. What the site pages do establish is the following.

What the PK literature on the site actually shows

• The effect is small in magnitude. The PEAR REG program reported a cumulative effect on the order of 1 part in 10,000 bits per trial over 91 operators and 1,000+ series (z ≈ 3.8). That is a headline positive result, but the same page stresses that at this magnitude individual studies are chronically underpowered.

• A major replication attempt was null. The MegaREG experiment — powered to detect the PEAR-reported effect — returned a null result. The page notes this cannot straightforwardly falsify the effect (a protocol-sensitivity reading remains open), but it is precisely the kind of result that argues against a rising, robustly reproducible effect.

• The apparent effect may be inflated by a few outliers. On the Mario P. Varvoglis page, Varvoglis and Bancel argue that two outlier participants in the PEAR benchmark micro-PK study contributed roughly a quarter of all trials and most of the total deviation — supporting an interpretation that the population effect size was overestimated, which helps explain the three-lab consortium replication failure. That is an argument for a smaller true effect, not a growing one.

• Meta-analytic PK effects are positive but small. Dean I. Radin’s meta-analyses — of 148 dice-fall studies and of 800+ random-event-generator experiments — report small positive effects that survive some quality controls (see the Dean I. Radin page). These are cross-sectional summaries, not time-trend analyses, so they don’t speak to increase-over-time either.

On effect size and time

The one clearly documented directional pattern in the PK material is about downward pressure and non-replication over time — the MegaREG null, the outlier-inflation critique, and the consortium replication failure — not an increase. This is a recurring theme in parapsychology more broadly (the “decline effect” and shrinking effects under tightened protocols), but I’m flagging that as general background, not something the retrieved numbered sources here quantify.

A caution on the moderator literature: Marilyn J. Schlitz’s work on the Schlitz page documents that participant motivation, belief, and sender–receiver relationship quality appear to modulate effect size in intention-related studies (DMILS/remote-staring), meaning unselected samples may underestimate effects present in motivated pairs. That is about which conditions produce larger effects, not about a temporal trend — and it is DMILS/distant-intention work rather than micro-PK proper, so it doesn’t answer the increase-over-time question.

Bottom line

• No retrieved source gives a 50-year effect-size trajectory for PK, so I can’t state that it rose, fell, or held steady with a number behind it.
• The documented signals — small baseline magnitude, a powered null (MegaREG), and an outlier-inflation critique suggesting the early effect was overestimated — point away from “increasing” and toward “small, heterogeneous, and harder to replicate under tighter protocols.”

For the fullest treatment, the PEAR Lab audit page is the most directly relevant deeper dive.