is a Latin word that literally means "I shall please". A placebo
is a substance which does not cause any physiological response,
such as a sugar pill. Sometimes, a doctor may give a patient
a placebo to satisfy the patient's demand for a drug.
It is very common for individuals given a placebo to report
an improvement in symptoms. This is sometimes called the "placebo
effect". Since this improvement cannot (by definition) be
due to the action of the placebo, it may reflect the psychological
effect of the subject's belief in the benefit of the pill.
In research studies to determine the efficacy
of a new drug, some subjects may be given the experimental
drug and some subjects may be given a placebo. The purpose
of this procedure is to control for the placebo effect. Subjects
are not told which kind of pill they have been given. Thus,
if subjects given the test drug report experiencing some side
effect (e.g., nausea) while subjects given the placebo do
not, the experimenters would conclude that nausea is a valid
side effect of the drug. However, if subjects given the placebo
and subjects given the drug both report an improvement in
migraines, the experimenters should conclude that the drug
does not provide any better migraine relief than a placebo.
by Catherine E. Myers. Copyright © 2006 Memory Loss and the Brain