The theoretical basis of systematic desensitization is reciprocal inhibition in which an alternative, competitive response to anxiety is conditioned to arousal-producing, phobic stimuli. Abbreviated training in progressive relaxation is believed to serve as a competitive response to anxiety by decreasing autonomic nervous system activity. However, physiologic studies of progressive relaxation have not substantiated that its practice is associated with such decreased autonomic activity. Consequently, the use of progressive relaxation has been a confounding factor in the determination of the function of reciprocal inhibition in systematic desensitization. To confirm and refine the theoretical constructs of reciprocal inhibition, it is necessary to test the effects of a response which is competitive to the anxiety response. Such a response may be the relaxation response which is characterized by physiologic changes consistent with decreased autonomic nervous system activity. Derived from meditational practices, techniques which elicit the relaxation response incorporate the element of focused attention which has been implicated as a critical factor in systematic desensitization. Thus, the use of the relaxation response should be a more appropriate method than progressive relaxation if the therapeutic usefulness of systematic desensitization is indeed due to reciprocal inhibition.
