The answer is a self-fulfilling prophecy.
A self-fulfilling prophecy is a false definition of a situation or a person that evokes a new behavior, which causes the false conception to become true. This deceptive validity perpetuates the error. The possessor of the false belief will perceive the course of events as proof that he was right from the beginning.
For example: When a person believes that he is going to fail an exam, his fears cause that failure to be confirmed.