Principal investigator: mgr Justyna Brączyk

Funding Agency: Narodowe Centrum Nauki
Funding Scheme: PRELUDIUM

It is not uncommon for medical doctors to include placebos in the treatment of their patients. The placebo effect occurs when a pharmacologically inactive substance or procedure (e.g. sugar pill, sham surgery) has a beneficial impact on our health. Although this kind of treatment may be effective in relieving many symptoms and diseases, it is being criticized as unethical - mainly for requiring patients to be misled. However, there is growing evidence that shows that it is possible to obtain the placebo effect even when participants know that they receive inactive substances. Placebo administered openly, successfully diminished a variety of bothersome symptoms, and its effectiveness was often comparable with deceptive placebo use. Therefore this effect seems very promising for clinical practice, nevertheless, it has not been fully understood yet. 
The standard placebo effect (based on misleading the patients) in the field of pain is proved to be successfully induced by four methods. One of them is a verbal suggestion that a certain substance or procedure will alleviate the pain sensation. The second is called observational learning and it is based on acquiring behaviors through the observation of another person. Observation of the person who has experienced decreased pain after the use of placebo may also reduce the observer’s pain sensation in the similar situation. What is more, the placebo effect can be induced by previous direct experience. If the previous experience was based on evoking association between the placebo substance and the active treatment, we call it classical conditioning. If the reaction to the pain stimulation was previously followed by a desired or unpleasant event and is therefore more or less likely to occur in the future, we call it operant conditioning. All these methods of inducing deceptive placebo effects in the field of pain are well established and are still being developed. In contrast, not much is known about methods of inducing the open-label placebo effect. So far, it was evoked only by verbal suggestions or by verbal suggestions combined with classical conditioning.