Sorry, late jumping in...
Background: I've studied dowsing, as applied to treasure hunting, for about 5 years. Have met, both personally and virtually (forums), many treasure dowsers. Have read several books on the subject of dowsing, and many articles. Have purchased a number of treasure dowsing devices (called long-range locators (LRLs)), and found them to be bogus. Currently offer a $10,000 prize to any LRL manufacturer who can demonstrate that their device can really detect gold.
Three comments to Peter:
In my experience with treasure dowsers, most do not recognize ideomotor action as a cause of the dowsing response. In fact, many of them vehemently deny it, when it is brought up. Why? As far as I can tell, admitting ideomotor as a cause of movement, implies that the trigger would have to be psychic in nature. I guess they don't want to believe that their dowsing abilities are psychic.
This is supported by the many attempts to assign physical explanations to the response, through all sorts of bogus science. LRL manufacturers take advantage of this, by supplying chemically-enhanced and electronically enhanced dowsing devices, complete with nonsensical "scientific" theories of operation, for thousands of dollars each. See http://www.treasurenow.com for some examples of what you can buy, and http://www.thunting.com/geotech/pages/lrl (click Reports) for some examples of what you really get.
From what I've read about water dowsers, many of them also assign physical explanations to their abilities. Such as electromagnetic fields, electrostatic potentials, etc. I suspect that quite a few believe that the dowsing device responds directly to these forces, not to their own hand movement.
Regarding proper testing and odds, I agree that dowsing tests are not always optimal. I've posted before, that testing groundwater dowsing is phenomenally difficult, and phenomenally expensive. Therefore, I suspect that Randi seeks a cheaper alternative, such as water-pipe dowsing, as long as the claimant agrees that such a method is a valid test of his ability. If he fails the test, then he has the option of saying, "That test was not a valid method after all," or "I could not dowse today, maybe tomorrow," or "I cannot dowse at all."
Any dowser who claims to dowse groundwater, is certainly free to say that he cannot dowse water pipes, and insist on a true groundwater test protocol. Randi would be obliged to provide for such a test, at his expense, or to decline entirely. Don't know if that scenario has ever come up.
In the odds department, I also agree that sometimes dowsers score a bit above chance (and sometimes a bit below), and the test should be extended to check for a real ability, if that knowledge is desired. But again, from my 5 years of treasure-dowser experience, dowsers don't tend to claim a slightly-better-than-chance ability... most believe that they are 100% accurate, or close to it. Thus, if they readily agree to a high-success threshold, a slightly-better-than-chance result is a failure per their claim.
One of the better dowsing tests that I've read about, is the "Scheunen" test done in Germany, that involved a few hundred dowsers. Those that scored significantly above chance, were re-tested, and their second attempts were unimpressive. Again, with Randi's challenge, any dowser is free to claim a slightly-better-than-chance ability, and Randi would have to design a test that accomodates that claim. It just means that the test takes a lot longer.
Background: I've studied dowsing, as applied to treasure hunting, for about 5 years. Have met, both personally and virtually (forums), many treasure dowsers. Have read several books on the subject of dowsing, and many articles. Have purchased a number of treasure dowsing devices (called long-range locators (LRLs)), and found them to be bogus. Currently offer a $10,000 prize to any LRL manufacturer who can demonstrate that their device can really detect gold.
Three comments to Peter:
In my experience with treasure dowsers, most do not recognize ideomotor action as a cause of the dowsing response. In fact, many of them vehemently deny it, when it is brought up. Why? As far as I can tell, admitting ideomotor as a cause of movement, implies that the trigger would have to be psychic in nature. I guess they don't want to believe that their dowsing abilities are psychic.
This is supported by the many attempts to assign physical explanations to the response, through all sorts of bogus science. LRL manufacturers take advantage of this, by supplying chemically-enhanced and electronically enhanced dowsing devices, complete with nonsensical "scientific" theories of operation, for thousands of dollars each. See http://www.treasurenow.com for some examples of what you can buy, and http://www.thunting.com/geotech/pages/lrl (click Reports) for some examples of what you really get.
From what I've read about water dowsers, many of them also assign physical explanations to their abilities. Such as electromagnetic fields, electrostatic potentials, etc. I suspect that quite a few believe that the dowsing device responds directly to these forces, not to their own hand movement.
Regarding proper testing and odds, I agree that dowsing tests are not always optimal. I've posted before, that testing groundwater dowsing is phenomenally difficult, and phenomenally expensive. Therefore, I suspect that Randi seeks a cheaper alternative, such as water-pipe dowsing, as long as the claimant agrees that such a method is a valid test of his ability. If he fails the test, then he has the option of saying, "That test was not a valid method after all," or "I could not dowse today, maybe tomorrow," or "I cannot dowse at all."
Any dowser who claims to dowse groundwater, is certainly free to say that he cannot dowse water pipes, and insist on a true groundwater test protocol. Randi would be obliged to provide for such a test, at his expense, or to decline entirely. Don't know if that scenario has ever come up.
In the odds department, I also agree that sometimes dowsers score a bit above chance (and sometimes a bit below), and the test should be extended to check for a real ability, if that knowledge is desired. But again, from my 5 years of treasure-dowser experience, dowsers don't tend to claim a slightly-better-than-chance ability... most believe that they are 100% accurate, or close to it. Thus, if they readily agree to a high-success threshold, a slightly-better-than-chance result is a failure per their claim.
One of the better dowsing tests that I've read about, is the "Scheunen" test done in Germany, that involved a few hundred dowsers. Those that scored significantly above chance, were re-tested, and their second attempts were unimpressive. Again, with Randi's challenge, any dowser is free to claim a slightly-better-than-chance ability, and Randi would have to design a test that accomodates that claim. It just means that the test takes a lot longer.