Demand effects for desensitization and two placebos in a dental fear context.

Forty-five subjects sampled two sessions of a prototype desensitization treatment, two sessions of the Modified Avoidance Response Placebo or two sessions of Pseudotherapy. Each subject simulated the effects on dental fear of the experimental regimen to which he was exposed. Each subject also rated the credibility of the sampled regimen. Both the simulation data and the credibility ratings showed the Modified Avoidance Response Placebo to be the preferred control for "nonspecifics" in dental-fear desensitization experiments.