According to psychologists, it is quite the opposite. It is known as the Benjamin Franklin effect . The premise is that someone who has already done you a favor is more likely to do it again than if you do something for them. The underlying theory is based on cognitive dissonance. Basically we rationalize our actions and feelings so that they are consistent with each other. Someone who has already done you a favor will rationalize that they did it because they like you and are therefore more likely to do another.