A self-fulfilling prophecy is a prediction that comes true at least in part as a result of a person's belief or expectation that the prediction would come true. In the phenomena, people tend to act the way they have been expected to make the expectations come true. Self-fulfilling prophecies are an example of the more general phenomenon of positive feedback loops. A self-fulfilling prophecy can have either negative or positive outcomes. Merely applying a label to someone or something can affect the perception of the person/thing and create a self-fulfilling prophecy. Interpersonal communication plays a significant role in establishing these phenomena as well as impacting the labeling process.

In the case of uncertainty, expectation is what is considered the most likely to happen. An expectation, which is a belief that is centered on the future, may or may not be realistic. A less advantageous result gives rise to the emotion of disappointment. If something happens that is not at all expected, it is a surprise. An expectation about the behavior or performance of another person, expressed to that person, may have the nature of a strong request, or an order; this kind of expectation is called a social norm. The degree to which something is expected to be true can be expressed using fuzzy logic. Anticipation is the emotion corresponding to expectation.