ABSTRACT
Both the research and practice of clinical psychology have undergone dramatic changes throughout the last century. During the first half of the century, both psychotherapy and the concomitant effectiveness research were largely unstructured. Typically, diagnostic categorieswere unreliable; treatment strategies were poorly defined; measurements were not standardized, and subjects were not randomly assigned to treatment conditions. Although these early efforts to investigate the effectiveness of psychotherapy began a valued tradition of holding psychotherapists accountable for their outcomes, the lack of methodological rigor led to some discouraging conclusions about psychotherapy effectiveness.HansEysenck, a pioneer in psychotherapyoutcome research, conducted two large-scale qualitative literature reviews in 1952 and 1960 in whichhe concluded that,with the exceptionof behavior therapy, psychotherapy adds little or nothing to the simple passage of time or treatment by a general medical practitioner (Eysenck, 1952). Not surprisingly, Eysenck’s findings elicited a wave of concern in the psychological community about the validity of the research that led to these bleak conclusions. Of paramount concern was the fact that the vast majority of the reviewed studies had uncontrolled designs, weak methodology, ill-defined subject groups, insufficiently described treatments, unidimensional outcome measures, and no follow-up data. Critics of Eysenck’s findings argued that the studies had such low internal validity that it would be impossible to conclude anything regarding the effectiveness of psychotherapy. This uprising catalyzed a movement toward efficacy studies focused on enhancing internal validity.
