We RETURN FAVORS and exchange gifts. Sometimes we do this out of love or for fun. But many times we give gifts or favors out of a sense of obligation. If I give you a gift or do you a favor, you will feel indebted to me. You will want to give me a gift or do me a favor in return; possibly to be nice, but mainly to get rid of the feeling of indebtedness. This is a largely unconscious feeling, and it is quite strong. This is called reciprocity.