Scientific studies
There have been many investigations of the veracity of dowsing. The positive studies were mostly informal and did not meet scientific standards. These studies failed to exclude alternate explanations such as environmental clues in open terrain. A well-designed study would have blinded the dowser and the experimenter. Furthermore, any study must be carefully analyzed for statistical significance before conclusions can be drawn.
Sydney
An early objective scientific test of dowsing was performed in Sydney, Australia, in 1980.[1] The tests were supervised by James Randi and Dick Smith who offered a $40,000 reward to the first successful participant. The reward offer was an early version of what has since developed into Randi?s million dollar challenge, under which hundreds of dowsers have since been tested. As of 2006, they have all failed to demonstrate any objective dowsing ability.
In the Sydney test there were 16 contestants; not a large number, but entirely sufficient given the discrepancy between the 10 per cent success rate expected due to chance and the 92 per cent success rate the dowsers expected to deliver. The main experiment used a grid of 10 plastic pipes, four inches in diameter, buried parallel to each other a few inches below the soil surface. The position of the pipes was marked on the ground, and in each test water flowed in only one of them, so the dowsers simply had to select one of the 10 pipes.
The contestants agreed to all the procedures prior to the test. They were also allowed to dowse the field with no water running to determine whether there might be any interfering natural phenomena, and to dowse the field with water running in a known pipe to verify (subjectively) their sensitivity to it. Similar tests were designed for contestants who believed they could find brass or gold. In all, 111 trials were made. There were 15 successes, which is well within the range (around 11) expected by chance.
Munich
The most extensive scientific study of dowsing to date was done in Munich, Germany, in 1987 and 1988 and published in 1989.[2] More than 500 dowsers participated in more than 10,000 double-blind tests.
In one series of tests, the dowsers were in a long, movable wagon with no windows. The idea was to recreate conditions as close as possible to the normal working conditions of dowsers ? within the limits of scientifically controlled experiments ? and to make as few assumptions as possible about the nature of dowsing. The dowsers were asked to identify the position on the floor of the wagon at which they detected a disturbance. The wagon was then moved and they were asked to find the same spot. If they were actually detecting something under the ground, whatever it was and whether or not it was the same thing other dowsers detected, the spot they picked should have been over the same spot on the ground regardless of where the wagon was standing. This setup was remarkable for its generality, although it was too complicated and expensive to be used to test large numbers of dowsers. Within statistical uncertainties, the participants failed to show any dowsing ability in this test.
The largest number of tests were done in a barn. On the ground floor, water was pumped through a pipe that could be moved in a direction perpendicular to the flow. The participants on the upper floor were asked to determine the position of the pipe. Some 500 dowsers were tested in this way. Of these, the 43 dowsers who seemed to be the best were chosen to undergo more extensive tests. Over two years, a total of 843 single tests were made with this group. This experimental setup and the data obtained from it were generally agreed by the dowsers, the experimenters, and the critics to be scientifically valid and a fair test of dowsing ability.
Of the 43 pre-selected and extensively tested candidates, at least 37 of them obviously showed no dowsing ability. The results from the remaining 6 were slightly better than chance. The authors concluded that this result is statistically significant and indicative of a weak but real dowsing ability. A number of scientists have strongly and in detail contended that these results are consistent with statistical fluctuations in the absence of any real ability.
Kassel
More recently a scientific study[3] was undertaken in Kassel, Germany, under the direction of the Gesellschaft zur wissenschaftlichen Untersuchung von Parawissenschaften (GWUP) [Society for the Scientific Investigation of the Parasciences]. The three-day test of some thirty dowsers involved plastic pipes through which a large flow of water could be controlled and directed. The pipes were buried 50 centimeters under a level field. On the surface, the position of each pipe was marked with a colored stripe, so all the dowsers had to do was tell whether there was water running through the pipe. All the dowsers signed a statement agreeing this was a fair test of their abilities and that they expected a 100% success rate. However, the results were no better than what would have been expected by chance.
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