The Marshmallow Test
Back in the day, before Facebook, Amazon, YouTube, Google, and the iPhone a psychologist named Walter Mischel, PhD, explored self-control in children. 40 years ago, he performed a simple experiment that was highly effective at determining a child's level of self-control. This experiment is commonly referred to as "the marshmallow test," and has led to the study of delayed gratification.
Here's how the experiment was implemented:
Mischel and his colleagues presented a preschooler with a plate of treats such as marshmallows. The child was then told that the researcher had to leave the room for a few minutes, but not before giving the child a simple choice: If the child waited until the researcher returned, she could have two marshmallows. If the child simply couldn't wait, she could ring a bell and the researcher would come back immediately, but she would only be allowed one marshmallow.
(pay particular attention to the results of the follow up on page two.)