Final answer:
The self-fulfilling prophecy is the concept used to explain reciprocal liking, where one's beliefs about another's feelings can lead to actions that result in those feelings becoming true.
Step-by-step explanation:
The concept that can be used to explain the notion of reciprocal liking is the self-fulfilling prophecy. A self-fulfilling prophecy occurs when a person's beliefs or expectations about another lead to the realization of those beliefs or expectations. For example, if you believe someone likes you and therefore act more friendly towards them, it is likely that they will reciprocate that friendliness, thereby confirming your initial belief. This concept is relevant to social psychology and is particularly interesting when studying interpersonal relationships and attraction.