Reference here: The Marshmallow Test: Psychological Experiments in Self-Control
In this reprise of a now-classic Stanford psychological experiment from the 1960s, kids are put in a room with a marshmallow and told they can either eat it immediately or wait until the researcher gets back, and they'll be given a second marshmallow. Hilarity ensues as the kids suffer marshmallow temptation!
But the consequences go deeper: In the New Yorker article "Don’t!" from May that detailed the very same experiment, it turned out that the ones who passed the marshmallow test enjoyed greater success as adults. Said Walter Mischel, the Stanford professor of psychology in charge of the experiment, "What we’re really measuring with the marshmallows isn’t will power or self-control... It’s much more important than that. This task forces kids to find a way to make the situation work for them. They want the second marshmallow, but how can they get it? We can’t control the world, but we can control how we think about it.”