Double blind, Satan's UFO, failed prophecies.(Twas Brillig...)

How to Conduct a Double Blind Experiment

At the James Randi Educational Foundation (JREF) we have had several requests from potential prize applicants who believe that they have the power to dowse, and who need general guidelines on how to conduct a double-blind test before they actually make application. We recognize that not everyone will know what a double-blind test is, so here is a general description.

The term "double-blind" refers to the condition under which neither the subject of the experiment--in this case, the dowser--nor the experimenter, knows the answer that is being sought. As one example, we tested a very enthusiastic dowser named Mike Guska at the JREF headquarters in Fort Lauderdale. He claimed that he could detect gold. When we suggested that the gold sample he had brought with him--a genuine gold nugget--should be concealed in one of ten opaque, numbered, and sealed Styrofoam cups, he agreed that that would be an adequate test.

Before we began, I had him "scan" the entire floor space of our library, where the test was to take place. This was to allow him to determine whether or not there were any distractions present that might mislead him or give him a false reading. Indeed, he found two spots where he said there were anomalies, and these were plainly marked off as not suitable to be included in the test area. (It is of" interest to note that other dowsers, given the same opportunity, have also determined such spots, but significantly, no two dowsers have ever located the same spots!) We then placed the Styrofoam cups, uncovered, at various points in the room. By randomly selecting a numbered ball from an opaque bag, we arrived at a number between one and ten, and openly placed the gold nugget he had brought with him, into that cup. He was then asked to scan the area with his dowsing stick to determine if it would be attracted to the gold sample. It apparently was, to his satisfaction. We repeated this "baseline" demonstration 10 times, changing the cups and it was always successful.

We had now determined that his dowsing method should work under the circumstances established.

Now we were ready to perform the double-blind test. Both the dowser (the subject) and I (the experimenter) stepped out of the room while another person, who was continuously videotaped, went through the randomization process, placed the gold sample in the selected cup, and sealed it with a lid. Then she left the room and called out to us to proceed.

Both of us (subject and experimenter) reentered the room, and the subject walked about with his dowsing rod, finally selecting the one in which he believed the gold had been enclosed. We entered that guess on a list, and both signed the entry. Then we left the room together and called out to the third party to reenter the room and repeat the process.