Reframing treatment expectations: a lay theory perspective for understanding individuals’ beliefs about psychotherapy

Psychotherapy expectations are considered one of the common factors influencing therapeutic success. Two broad dimensions of psychotherapy expectations have been identified: expectations about treatment benefits (outcome expectations/OEs) and expectations about the therapy process (treatment expectations/TEs). Both dimensions have been previously investigated; however, the evidence of TEs has been restricted by methodological limitations and the lack of an overarching theory to guide in-depth investigations. This state of affairs likely contributes to an ongoing under-estimation of expectation effects in psychotherapy, which tend to lag behind current knowledge about placebo effects. The aim of this paper is to present the rationale for adopting a "lay theory of psychotherapy" approach as a conceptual model for TEs. Based on its theoretical assumptions, it is suggested that these lay theories of psychotherapy can be operationalized as individuals' change process expectations, or what individuals view as the expected mechanism producing therapeutic change. Core components of lay theories and their operationalization as change process expectations are discussed, including their associations with process, role, and duration expectations, their dynamics, their associations with OEs, and their predictive effect on therapy outcomes. A review of literature supporting this model is presented, as well as directions for future research assessing its validity.