Answer: Placebo effects.
Step-by-step explanation:
Placebo effect is also known as Placebo, it is a situation whereby a substance known to have effective performs the wonders of improving the health condition of a patient, this is due to the believe the patient has towards the substance. One of the factors that helps Placebo effect is "Expectation".
A substance is regarded to have placebo effect if it was not designed to have any therapeutic value, Examples of placebo includes disabled water, sugar, sham surgery, inert injection and tablets, etc.