Effects of suggestion on d' and Cx for pain detection and pain tolerance.

It has been demonstrated that suggestion directed toward eliciting fewer reports of detection of minimal pain and suggestion directed toward greater pain tolerance (fewer withdrawals) altered the response probabilities in the expected direction and in addition raised both the pain detection and pain tolerance thresholds to thermal stimulation. However, sensory decision theory analysis of the same response data revealed that the sole effect of the suggestions was to raise the detection criterion for very faint pain (CVFP) and the withdrawal criterion for pain tolerance (Cw). Suggestion was absolutely without effect on the subject's ability to discriminate noxious stimulation, d', indicating that suggestion had failed to produce an analgesic effect. Males set a higher criterion than females, but d' did not differ. It may be concluded that many of the pain threshold changes produced by "cognitive control," hypnosis, counterirritant stimulation, etc., are not due to decreased pain sensitivity but merely reflect changes in the criterion for reporting pain.