Experimenter Effect and Replication in Psi Research
Marilyn Schlitz*3, Daryl J. Bem4, Eva Lobach8, Thomas Rabeyron7, William Bengston9, Sky Nelson3, Serena Roney-Dougal5, Garret Moddel10, Patrizio E. Tressoldi6 & Arnaud Delorme1,2,3

1. Paul Sabatier University, Toulouse, France
2. University of California, San Diego
3. Institute of Noetic Sciences, Petaluma, CA
4. Cornell University, Ithaca, New York
5. Psi Research Centre, Somerset, Britain
6. Università di Padova, Italie
7. Université de Nantes, France
8. University of Amsterdam, The Netherlands
9. St Joseph College, New York
10. University of Colorado, Boulder, CO

This study addressed the replication problem in parapsychology through the examination of experimenter and participant belief in psi and their impact on the outcome of a psi task. The meta-study involved an international collaboration of teachers, student experimenters, and experimental volunteers, who made use of a standardized psi protocol that has been the focus of a number of replication attempts and that allows for a systematic collection of data under well-controlled conditions (Bem, 2011). It included 12 different laboratories across 32 experimenters and 512 participants. While the preregistered hypothesis that was assessed on a participant basis did not show a significant psi effect, when the statistical power was increased by using a single trial analysis, the primary hypothesis was highly significant. The results did not support a correlation between study outcome and experimenter expectancy. Overall, these results support the feasibility of a multi-laboratory collaboration and show that single trial analysis might be more appropriate and powerful to process these types of data.