Conducted by Walter Mischel at Stanford.
Children were offered a choice: One marshmallow now, or two if they waited 15 minutes.
Follow-up studies showed those who waited had better SAT scores and life outcomes.
However, recent replications suggest socioeconomic background plays a larger role. If you don't trust the promise of "later," eating now is rational.
Developmental
Marshmallow Test
Can a 4-year-old's patience predict success?