The marshmallow experiment is a well known test of this concept conducted by Walter Mischel at Stanford University and discussed by Goleman in his popular work. In the 1960s, a group of four-year-olds were given a marshmallow and promised another, only if they could wait 20 minutes before eating the first one. Some children could wait and others could not. The researchers then followed the progress of each child into adolescence and demonstrated that those with the ability to wait were better adjusted and more dependable...
.wikipedia.Deferred_gratification
(Amazon.com)