Within the study of the psychology of relationships is a principle called reciprocity, which speaks to the human need (and tendency) to want to give something back when something is received. People feel a sense of obligation to do something for you when you’ve done something for them.
Reciprocity affects us every day. Have you ever: Invited someone to your wedding because they invited you to theirs; bought a Christmas gift for someone because they bought one for you; donated money to an organization or subscribed to a magazine/newspaper because they offered a free gift?
