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In this example, the problems with the people's digestive system were psychosomatic. They expected to have health problems when their water was fluoridated so when they thought it was fluoridated, they had issues. This is an example of the nocebo effect, because the results were adversely psychosomatic. This is the opposite of the placebo effect, which is when a patient or subject improves because of the belief that a certain treatment will benefit them.