On a recent episode of Radiolab (the NYC radio show/podcast), there was an episode that interviewed Walter Mischel (pronounced like the girl's name, Michelle). You can find it here. He described the studies he did, the role of his daughters as an impetus, and a Q/A with Jad Abumrad, one of the hosts. Mischel found a profound difference between kids who were able to wait to eat the marshmallows versus eating them immediately, when age 4 and had SAT scores.
The kids who could not wait were later more likely to wind up as the bullies, had more detentions and suspensions. Mischel continued following the kids (who were adults in their 40s). The more data they collected, the more the differences continued.
There are different explanations as to why the kids were able to wait-is self-control hard-wired or are diferent strategies the explanation--showing that this can be taught. Or is it some combination??? Fascinating.
ABC reenacted the study for the demonstration. http://www.youtube.com/watch?v=4CYr4FgMYGI&feature=related . There are a number of related videos and replications at this link.