[Seeing others is believing-analgesic placebo effects through observational learning?].

Background: There are many studies on placebo analgesia and its underlying mechanisms that show a significant improvement of care for chronic pain patients. However, observational learning has not been researched to this degree.

Objectives: The goal of this work is to provide an overview of the research on placebo analgesia via observational learning. The evidence around whether observational learning can induce placebo analgesia will be discussed. Also, research on the factors that influence observational learning of placebo analgesia will be reviewed.

Materials And Methods: To this end, research data bases were searched for studies on placebo analgesia via observational learning.

Results: After inclusion and exclusion criteria were implemented, 12 studies remained. To date, there has been only one study with patients with chronic pain. The small number of included studies do not permit universal statements. However, there is preliminary evidence that observation triggers placebo analgesia as an independent mechanism. Observational learning in an experimental setting can induce placebo effects. Attention focusing on the observation might be critical. The effect sizes tend to be small to large. The effect of classical conditioning and observational learning seem to be of equal size. Live models, video recordings and even pictures of models also induce similar effects. Observational learning induces a change in expectation.

Discussion: The evidence included provides the theoretical basis for potential significant clinical impact. Further research is needed to extend these findings to chronic pain patients.