Abstract
Evidence-based psychotherapy requires clinicians to consider theories of psychopathology and evidence about effectiveness, and their experience when choosing interventions. Research on clinical decision making indicates that clinicians' theories of disorders might be personal and inform judgments and choices beyond current scientific theory and evidence. We asked 20 child therapists to draw models of how they believed that biological, psychological, environmental, and behavioral factors interact to cause and maintain four common developmental disorders. They were also asked to judge the effectiveness of interventions recommended in the literature. Therapists showed only fair agreement about the factors and a slight to fair agreement about the causal relations between these, and just fair agreement about interventions' effectiveness. Despite these disagreements, we could predict effectiveness judgments from therapists' personal theories, which indicates that clinicians use personal theories in decision making. We discuss the implications of these findings for evidence-based practice.