Placebo effects are health improvements, for example pain reduction, due to an inert treatment. These effects are typically ascribed to a person’s expectations about the beneficial outcomes of the placebo.
The literature and experimental research in the current dissertation shows that expectancies, and thereby placebo effects, can be induced via verbal suggestion, conditioning, and mental imagery. Especially verbal suggestions may enhance analgesic treatments for patients. We found, for the first time, that mental imagery of reduced pain can induce analgesia via its effects on pain expectancies. We also observed that people’s expectations about the effectiveness of medications depend on the route of administration and targeted symptom.
These findings suggest that harnessing placebo effects by targeting expectancies is promising for enhancing standard clinical care of physical symptoms.