The most important aspect of any medical experience is its content. Whether a physician or healer prescribes aspirin or penicillin, willow bark tea or quinine, the most crucial thing is that the drug has some sort of active ingredient which interacts with the body, the immune system, a pathogen or the like, to facilitate recovery. But the content of medicines is not the only thing that counts. We have just reviewed the effect that physicians - their knowledge, their enthusiasms - can have on treatment. The form of medicines, their color, shape, and amount, makes a difference, too.

Meaningful pills (pink and blue ones)

In the early 1970s, several professors at the University of Cincinnati medical school devised an interesting experiment for their students (Blackwell, Bloomfield, and Buncher 1972). Fifty-seven second-year medical students agreed to participate in what they were told was a study of two new drugs. Each student would receive either a stimulant or a sedative. They were told the ordinary effects of these drugs. For example, they were told that “a sedative drug usually makes the individual feel more relaxed, calm and easy-going, but some people react by feeling drowsy, sluggish or tired. There is a tendency toward a decrease in pulse-rate, pupil size, and arterial [blood] pressure.” The students were randomly divided into four groups. These groups received, respectively, one or two pink or blue tablets; the tablets were, in fact, inert.