It starts with a group of Stanford psychologists in the 1960s, led by Walter Mischel. Mischel used a small research room at the Stanford University preschool, and he posed the following scenario to the kids in the study:
"Here's one marshmallow for you. I am going to give it to you and leave the room. While I'm gone, you can eat it, or not, it's up to you. When I come back, if the marshmallow is still here, you get TWO marshmallows because I will give you another one. "