Kaptchuk had divided people with irritable bowel syndrome into three groups. In one, acupuncturists went through all the motions of treatment, but used a device that only appeared to insert a needle. Subjects in a second group also got sham acupuncture, but delivered with more elaborate doctor-patient interaction than the first group received. A third group was given no treatment at all. At the end of the trial, both treatment groups improved more than the no-treatment group, and the “high interaction” group did best of all.

Kaptchuk, who before joining Harvard had been an acupuncturist in private practice, wasn’t particularly disturbed by the finding that his own profession worked even when needles were not actually inserted; he’d never thought that placebo treatments were fake medicine. He was more interested in how the strength of the treatment varied with the quality and quantity of interaction between the healer and the patient — the drama, in other words. Hall reached out to him shortly after she read the paper.

The findings of the I.B.S. study were in keeping with a hypothesis Kaptchuk had formed over the years: that the placebo effect is a biological response to an act of caring; that somehow the encounter itself calls forth healing and that the more intense and focused it is, the more healing it evokes. He elaborated on this idea in a comparative study of conventional medicine, acupuncture and Navajo “chantway rituals,” in which healers lead storytelling ceremonies for the sick. He argued that all three approaches unfold in a space set aside for the purpose and proceed as if according to a script, with prescribed roles for every participant. Each modality, in other words, is its own kind of ritual, and Kaptchuk suggested that the ritual itself is part of what makes the procedure effective, as if the combined experiences of the healer and the patient, reinforced by the special-but-familiar surroundings, evoke a healing response that operates independently of the treatment’s specifics. “Rituals trigger specific neurobiological pathways that specifically modulate bodily sensations, symptoms and emotions,” he wrote. “It seems that if the mind can be persuaded, the body can sometimes act accordingly.” He ended that paper with a call for further scientific study of the nexus between ritual and healing.