Answer:
Placebo effect
Step-by-step explanation:
The placebo effect refers to a situation in which expecting that something will happen can make it happen. This is seen in medical studies where drugs are tested and some people receive a placebo which is something that looks like a drug but is not. It has been found that sometimes if someone expects a pill to do something, it is possible that the body's chemistry causes a similar effect like the one of the medication.
According to this, the answer is that people's expectations or beliefs influencing or determining their experience in a given situation is referred to as the placebo effect.