In a 1950 study, pregnant women who were experiencing nausea and vomiting were given a drug they were would cure their nausea. What they were actually given was ipecac, a drug given to cause vomiting. Their nausea and vomiting stopped entirely by taking a drug they believed would work. This was not just an improvement the women noticed it was also backed up with tests the researchers did before and after the women took the drug to monitor stomach contractions.

A 1987 study of 200 patients with non-specific complaints received either a “positive” or “negative” consultation. During the positive consultation, the doctor gave the patient a firm diagnosis and confidently remarked they could expect improvement within a few days. In the negative consultation, the patient was told, “I am not sure that the treatment I am going to give you will have an effect”. Both groups thought they were getting medication but received vitamins. 64% of the positive consultation patients got better within 2 weeks while only 39% of the negative patients improved.

Leaves from the Japanese lacquer tree causes a contact dermatitis like poison ivy. In 1962, 57 high school boys were blindfolded and one arm was brushed with leaves from the tree, the other arm was brushed with chestnut tree leaves that don’t cause anything. The boys were told they were brushed with chestnut tree leaves when they were actually brushed with leaves from the poisonous lacquer tree and vice versa. Within a few minutes the arm that was brushed with what the boys thought was poisonous, they began to experience burning and itching with raised red bumps. In most cases, the arm touched with the actual poisonous leaves did not react. The body created the reaction appropriate for what the mind believed.