Missing Mechanism Information

The first recommendation Kazdin made for advancing the psychotherapy research knowledge base, improving patient care, and reducing the gulf between research and practice was to study the mechanisms of therapeutic change. He noted, "The study of mechanisms of change has received the least attention even though understanding mechanisms may well be the best long-term investment for improving clinical practice and patient care" (p. 151). He clarified what he meant by mechanism by stipulating what it was and what it was not, and he provided examples. The point of this comment is to note that Kazdin (2008) omitted mention of an extensive and rapidly expanding literature on parallel distributed processing-connectionist neural network (PDP-CNN) models of cognition, affect, and behavior that provides psychologically relevant information on causal mechanisms. Kazdin's (2008) conclusion that learning more about causal mechanisms may best provide long term benefits to the science and practice of clinical psychology, including substantially mending the research-practice schism.