The Placebo Effect is a phenomenon in which a person's perception of their health or wellbeing is improved by taking a fake or inert treatment, such as a sugar pill or sham surgery. This effect is thought to be caused by the patient's belief that the treatment will be effective, leading to
From Wikipedia
A placebo is a medicine or treatment intended to appear genuine to its recipient, but which has no pharmaceutical effect. Common placebos include inert tablets, inert injections, sham surgery, and other procedures.