What the Communique Committed Both Sides To

The 1986 document does two things. It records an agreement, that the accumulated ganzfeld effect could not be explained by chance or by the file drawer alone, and it records the continuing disagreement about cause, with Hyman holding that an unidentified artefact remained the more probable explanation. Then it sets standards. Future studies were to use automated and documented randomisation, physical arrangements that made acoustic leakage between the rooms impossible rather than merely unlikely, full specification of the analysis before data collection, and complete reporting of every series begun rather than only those completed.

Read now, that list is unremarkable, because it describes ordinary practice in any pre-registered psychology experiment. In 1986 it was ahead of the mainstream discipline, which would not adopt comparable norms for another twenty-five years and did so partly under pressure from its own replication problems. The awkward legacy is that no ganzfeld series since has been agreed by both sides to have met the standard, and the two later meta-analyses that bear on the question, Milton and Wiseman in 1999 and Storm, Tressoldi and Di Risio in 2010, reach opposite conclusions on different study pools.