Wow.  Parents, take note.

This recent New Yorker article on the Stanford research is very compelling.

The test went like this: put a marshmallow on the table in front of a four-year-old; tell the child that he or she can either eat the marshmallow now, or leave it uneaten for a while (15-20 minutes) and receive a second marshmallow at the end of the test; have the researcher leave the room for the prescribed period of time; if the child sits alone with the marshmallow for the test period and does not eat the treat, the researcher returns and gives the child two marshmallows to eat. This a test of delayed gratification — the ability for a person to put off the instant thrill of one marshmallow for the promise of two marshmallows down the road.  (The research also involved treats other than marshmallows — including small toys and other treats — presumably to control for kids who just don’t like marshmallows.)

Here’s a snippet (emphasis added):

Most of the children [struggled] to resist the treat and held out for an average of less than three minutes. “A few kids ate the marshmallow right away,” Walter Mischel, the Stanford professor of psychology in charge of the experiment, remembers. “They didn’t even bother ringing the bell. Other kids would stare directly at the marshmallow and then ring the bell thirty seconds later.” About thirty per cent of the children, however, were like Carolyn. They successfully delayed gratification until the researcher returned, some fifteen minutes later. These kids wrestled with temptation but found a way to resist.

… Once Mischel began analyzing the results, he noticed that low delayers, the children who rang the bell quickly, seemed more likely to have behavioral problems, both in school and at home. They got lower S.A.T. scores. They struggled in stressful situations, often had trouble paying attention, and found it difficult to maintain friendships. The child who could wait fifteen minutes had an S.A.T. score that was, on average, two hundred and ten points higher than that of the kid who could wait only thirty seconds.

Two hundred and ten SAT points?  That's astounding!