Subject Expectancy and the Reduction of Cold Pressor Pain with Acupuncture and Placebo Acupuncture

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Abstract
Experimentally-induced cold pressor pain was used to compare acupuncture and placebo acupuncture and to assess the effect of subject expectancy on treatment outcome. A total of 72 [human] subjects were randomly assigned to 3 groups of 24 subjects. The first of two 60-s cold pressor trials was identical for all groups and served as a base-line. The 2nd trial was preceded by acupuncture for the 1st group, placebo acupuncture for the 2nd and no treatment for the 3rd. Within each of these 3 groups, expectancy was manipulated prior to the 2nd trial: 8 of the 24 subjects were led to expect less pain on the 2nd trial (high expectancy); 8 were led to expect no change in pain (low expectancy); and 8 were told that the effect of treatment could not be predicted (no expectancy). Numerical rating of pain intensity revealed no cases of dramatic pain reduction. Only subjects who received acupuncture treatment in conjunction with the high expectancy manipulation reported significant pain relief. Apparently, acupuncture involves more than placebo factors, but the treatment appears to require a positive attitude of the recipient to potentiate its effect.