Situational factors contributing to the placebos effect.

The influence of four variables (status of communicator of drug effects, attitude of dentist, attitude of dental technician, and message of drug effects) on the obtainment of placebo effects in an oral surgery clinic was investigated. Dependent variables were (1) rating of pain experienced from mandibular-block injection, (2) pre-post placebo state anxiety, and (3) pre-postplacebo fear of injection. Enthusiastic messages of drug effects produced statistically and clinically significant reductions in postplacebo fear of injection and state anxiety and markedly lower ratings of pain experienced during injection of local anesthetic. Although there was a strong tendency for positive placebo effects to occur when the dental staff was perceived as friendly and supportive, only the attitude factors obtained statistical significance. The status of the communicator accounted for very small portions of the variance.