there is also the effect of self-fulfilling prophecies. A self-fulfilling prophecy is a situation to come true. (For example, a teacher tells a class that they are especially intelligent and that semester the class does especially well on exams.) In marketing, a successful advertisement persuades consumers that a product works well; their belief causes them to use the product in such a way that it does work well. for example, the ads for Brand X of a diet pill say,