Peter is in a clinical trial for a new antidepressant and thinks he's getting a "real" pill; he actually starts to feel better just because he thinks he's getting treatment. When health improves due to the healing power of belief, it's called the effect.

Placebo effect

Explanation:

A placebo is an inactive substance or drug such as saline water or sugar pill, some people tend to feel better after being administered these inactive drugs. These individuals have faith in the healing power of drugs rather than actually the content of the drug and hence begin to experience improve health.

The placebo effect is defined as a phenomenon in which some people experience a benefit after the administration of an inactive substance or drug. The expectations of the patient play a significant role in the placebo effect; the more a person expects the treatment to work, the more likely they are to exhibit a placebo response.