Psychology is a diverse assortment of fields with distinct referents, often using the same terms, and it is not always easy to identify its shared assumptions. At base, the academic variants tend to include the notion that mental activity takes place in hard-to-access inner spaces, making it more appropriate to study behavioral manifestations of it, yet all of it can be represented in an expert language with a confusing relationship to physiological mechanisms. An Advanced Guide to Psychological Thinking: Critical and Historical Perspectives focuses on several key areas in psychology: learning, the brain, child development, and psychotherapy, and identifies several conceptual tensions that ground psychological understanding of various phenomena. These include a tension between "inside" and "outside," structure and function, higher and lower, and description and explanation; all have historically generated confusion at the heart of the discipline. As psychology was transformed into the