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Here’s an interesting study in how preconceptions influence our assumptions. The British Psychological Society Research Digest Blog (now that’s a mouthful) recently featured a story on how a new study may have shown that Ganzfeld telepathy experiments were influenced by experimenters:

Wooffitt said that a researcher’s choice to respond with “okay” or “mm hm” might seem inconsequential, but in fact the latter utterance clearly had an effect on the ‘receivers” confidence in their imagery. Consequently, he said, “it is at least possible that they [the ‘receivers’] will have less confidence in relying on their imagery to identify significant events or themes in the video clips.”

Interestingly, a number of people (both skeptics and psi proponents, and including one of my favourite blogs Mind Hacks) jumped to the conclusion that this new study was debunking the positive results for telepathy found in Ganzfeld research:

In this new study, psychologist Robin Woofit analysed the tapes of Ganzfeld experiments from the mid-1990s and found that experimenters were more likely to respond decisively to correct responses but give subtle cues (such as saying ‘mm hm’) to give more information when the response wasn’t initially accurate.

This suggests that some of the positive findings may be due to this subtle prompting which is known as the Clever Hans effect, after a horse who was thought to be able to do amazing calculations, until it was later discovered that he was simply clopping his hoof until his trainer responded in a positive way. (from the ‘Mind Hacks’ post)

What was not mentioned in the BPS story however – quite crucially – is that the Ganzfeld tests were double-blind, meaning that the experimenter could not in any way “give away” the correct answer. What this new study actually does is suggest an experimental flaw which may explain why skeptics get *negative* results from the Ganzfeld – because their attitude sows doubt in the mind of the ‘receivers’, causing them to question their first ‘guess’. As a consequence, assumptions such as those found in the Mind Hacks post are not only mistaken, they are utterly and completely incorrect…they have read the opposite conclusion into the study as to what the data shows.

Michael Prescott has commented about this on his blog as well.