Evaluation of acupuncture anesthesia: a psychophysical study

Four volunteers judged eight levels of thermal stimuli induced by a Hardy dolorimeter, varying in intensity from extremely painful to a low level seldom even perceived. Half of the 406 stimuli were applied during acupuncture and half either before insertion or after removal of the needles. The experimental design minimized or eliminated factors other than the needles themselves, i.e., no medication was given, the subjects were scientists accustomed to objectivity and, on a preceding day or days, all had become experienced in assigning numbers (individually chosen) to the sensations produced by the different stimuli. Galvanic skin resistance was also tested. The results did not show any influence of acupuncture on perception of pain or on galvanic skin resistance.