In 1972, a Stanford University psychologist conducted a study in which young children, individually, were offered either a small but immediate reward (a marshmallow or a pretzel) or a doubled reward if they were able to wait for 15 minutes. In follow-up studies, researchers found that children who were able to postpone gratification experienced better life outcomes as measured by such things as SAT scores, academic achievement, and body mass index.
Saying no to your child: The greatest and most painful of gifts
Parenting Advice