Drug developers are well-versed in the potential pitfalls posed by placebos. The dread "placebo effect" has done in more than a few experimental drugs which couldn't compete against the sudden response seen in patients who were given a sugar pill. Now investigators are exploring why so many people respond to a placebo--even when they know it isn't a therapy. "Right now, I think evidence is that placebo changes not the underlying biology of an illness, but the way a person experiences or reacts to an illness," Dr. Ted Kaptchuk, director of Harvard's Program in Placebo Studies and the Therapeutic Encounter, tells The Wall Street Journal. Story