Figure 1.

Schematic relationship between shared and non-shared nonspecific factors contributing to the placebo response in drug and psychotherapy: factors that are part of the (nonspecific) placebo effect in drug therapy (e.g., therapist empathy, intensity of patient-therapist communication, etc.) become “common factors” across all psychotherapies [Rosenzweig’s “Dodo Bird” (1936), or Lambert and Ogles’ “common factors” (2004)], addition to a (small) specific effect of the different psychotherapy modalities that may be composed of a specific combination of the factors, as listed in Table 1 .