Aims: The aim of this study was to integrate a series of recommendations, gathered via survey
from the research community in a previous piece of work (Pérez-Navarro, 2005), in a freeresponse
protocol and compare its efficacy with the standard Ganzfeld procedure.
Method: We used two experimental conditions: a standard Ganzfeld condition (N=50), and an
experimental condition integrating the researchers' recommended practices (N=50). These
included, among others, using successful target sets from previous studies, holding a preexperiment
informal chat, providing feedback to the sender, reviewing the individual’s comments
after the session, etc.
Results: Participants were more successful in the experimental condition that integrated the
researchers' recommendations (15 hits, 30%, z=0.82, p=0.21 vs. 11 hits, 22%, z=-0.49, p=0.31). This
difference did not reach statistical significance (z=0.92, p=0.18). Degree of success of the target
stimulus in previous studies was a strong predictor of the session outcome (rxy=0.39, p=0.004). In
a multiple lineal regression analysis post-session review contributed to the prediction of
performance with a significant coefficient of 0.15 (p=0.006).
Conclusions: Although the results obtained with the integration of the researcher's
recommendations in the experimental protocol was in the hypothesised direction, it did not reach
statistical significance at alpha=0.01. Therefore, we must be either far from understanding the
underlying mechanisms of ESP that would help us to unfold a fully visible version of the
phenomenon in the laboratory or, we must be, simply, dealing with a very weak effect.
Discussion: The Ganzfeld has been the result of long efforts towards the development of an
experimental protocol to replicate ESP. However, even if we assume that Ganzfeld meta-analyses
have proven ESP, there is still a problem of visibility, nowadays the main obstacle in this area in
terms of financial support, interdisciplinary co-operation, and effective dissemination and
acceptance of findings.