Open Administration of Placebos Greatly Increases Effectiveness

In postoperative pain following the extraction of the third molar (Levine et al., 1981; Levine and Gordon, 1984), a hidden intravenous injection of 6–8 mg morphine corresponded to an open intravenous injection of saline solution in full view of the patient (placebo). In other words, telling the patient that a painkiller was being injected (with …