The way patients experience pain can be directly influenced by providers' expectations of how successful the treatment will be, according to a study published in Nature Human Behaviour.
The study involved three experiments using two differently colored creams intended to relieve thermal pain, according to Science Daily. The creams were both placebos, but physicians were told that one was called "thermedol." The physicians were led to believe that thermedol was more effective than the other cream, a control. After the cream was applied to the patient's arm, thermal heat was used to assess how effective the cream was.
The first experiment included 24 pairs of physician and patients. The patient did not know which cream was applied on their arm, only the physicians knew. The patients who received thermedol reported less pain and said they believed it was more effective than the control cream. They also showed lower levels of psychophysiological arousal with the thermedol treatment.
Additionally, researchers captured patient's facial expressions that showed patients displayed less pain through their expressions when they received the thermedol treatment.
The other two experiments changed the order in which the creams were applied to patients' arms. This confirmed that the association between provider expectations and patients' pain experience was not due to the decrease of a conditioned response.
Study authors concluded that results of the study prove the existence of a "socially transmitted placebo effect."