Early response in psychotherapy: further evidence for the importance of common factors rather than "placebo effects".

Evidence is presented demonstrating that placebo control groups benefit more from psychotherapy than no-treatment control groups but less than patients who receive theory-driven treatments. Through a brief review of the results of comparative outcome studies, studies which compare patient outcomes for those seen by trainees or paraprofessionals versus professional therapists and those which show an early response of a sizable portion of patients, a case is made for the powerful effects of common factors in psychotherapy. The early response phenomenon has proposed another challenge to the unique effects of specific psychotherapies and to the wisdom of emphasizing the causative effects of specific techniques in the treatment of specific disorders.