Placebo pills work without deception

Kaptchuk et al. show that placebos administered without deception may be an effective treatment for irritable bowel syndrome. From Bakalar's summary:

They explained to all that a placebo was an inert substance, like a sugar pill, that had been found to “produce significant improvement in I.B.S. symptoms through mind-body self-healing processes.” The patients, all treated with the same attention, warmth and empathy by the researchers, were then randomly assigned to get the pill or not...At the end of three weeks, they tested all the patients with questionnaires assessing the level of their pain and other symptoms. The patients given the sugar pill — in a bottle clearly marked “placebo” — reported significantly better pain relief and greater reduction in the severity of other symptoms than those who got no pill.

A weakness of the study is that because the outcome measure is so subjective, placebo patients may have exaggerated their improvement to please the researchers.