The Conditioning Response
There's also the conditioning response to medical treatment, the belief that a drug administered by a doctor will do you good. Irving Kirsch, a psychologist at the University of Conneticut, believes the effectiveness of drugs such as Prozac may be attributed to the placebo effect. He analyzed 19 clinical trials of antidepressants and concluded that the expectation of improvement accounted for 75 percent of the drugs' effectiveness.

And lastly, the expectancy that taking a drug will have a powerful effect on your body. In one study, subjects given sugar water were told that it was an emetic. Over 80 percent of patients in the study responded by vomiting. As Asbjorn Hrobartsson, author of the study — The Uncontrollable Placebo Effect — puts it: "Any therapeutic meeting between a conscious patient and a doctor has the potential of initiating a placebo effect."

Many thousands of patients report relief from pain while taking placebos. Just because there is no medical explanation for this, is their recovery any less real?

The debate for and against placebos rages on. For many, it's a question of asking what difference does it make why something works, as long as it seems to work.

Richard Tonkin, M.D. of the Research Council for Complementary Medicine says, "The problem with the placebo effect is that it is regarded by most people as a nuisance or fake. But it isn't. It is a practical and positive effect that acts by catalyzing the self-healing mechanisms within a patient."