In the December Phactum Ed Gracely justified the high standards of evidence required by skeptics on the basis of the low a priori probability of the abilities we test. However, the unskeptical, Marcello Truzzi among them, claim that skeptics "don't play fair" and that we are continually "raising the hurdle." That's why I'd like to look at testing from the other side. After all, when a skeptic such as James Randi runs a test, the parties have always agreed in advance that the conditions are fair.
The test designer's aim is three-fold. Firstly, the test must be designed so that the results are statistically valid and unambiguous. Your wonderful method of determining the sex of an unborn child may work half the time, but don't expect that to impress a statistician.
Secondly, the test must be designed to eliminate the possibility of cheating. From long and sad experience skeptics know that many claims of paranormal ability are founded on self- delusion or outright fraud. The test design must eliminate these as far as is humanly possible.
It is the third aim of good test design which the unskeptical overlook. Success in the test should be easy for anyone who truly has the ability they claim. They need only demonstrate what they proclaim they can do.
When PhACT tested a therapeutic touch practitioner in 1996, we didn't expect her to jump any hurdles. She was feeling and fixing patients' human energy fields on a daily basis in her practice. Thus, we thought, it should be easy for her to demonstrate her ability to feel these fields. Sure enough, she could detect the difference in the fields around a healthy male arm and around an injured female arm with 100% accuracy -- when she could see the subject.
She had complete faith in her ability. She was sure she was using the field to distinguish between the subjects. She could feel it even through the thin fiberglass which screened the subjects' arms from sight. Thus, it would obviously make no difference to her if the subjects' bodies were hidden behind a curtain. Indeed, if she had been scientifically trained, she might have thought of carrying out some such test herself to confirm her ability.
Unfortunately, under those circumstances she chose the correct subject 11 times out of 20. This result is consistent with the null hypothesis, that is, that the "human energy field" cannot be detected or does not exist.
This test met the three criteria I mentioned above. Its results were statistically significant. The unblinded test showed 100% accuracy so the blinded test would be expected to give a similar result. (In practice we would have accepted a miss or two as being immaterial.) There were precautions. The subjects were selected randomly. The practitioner was out of the room while the subjects were being moved. No one on the practitioner's side of the curtain knew which subject was in position.
Finally, we were not expecting the practitioner to perform any unusual or difficult task. We just wanted her to demonstrate an ability which she was using every day to make her living. What could be fairer than that?
So, if you have a paranormal ability, show it to us and we'll believe. The test will be easy -- if you really have the ability. There are no hurdles -- unless you raise them!