Scientists conducted a study in the early 70's in which children were given a marshmallow and told that if they waited a few minutes, they could eat it an also have another one. If they couldn't wait, then they didn't get a second one. The results showed that the kids who waited were more successful and happier later on in school. If my daughter was in that experiment, she would pass with flying colors. In fact, to bribe her with a second marshmallow would be completely unnecessary.
I never understood the meaning of the phrase, “You can't have your cake and eat it, too” until I observed this behavior in her. I'd give her a treat, fully expecting her to shove it in her mouth as fast as she physically could. Instead, she holds onto it for HOURS -- smelling it, feeling it, and staring at it. It's amazing that she understands the concepts of delayed gratification and opportunity cost at such a young age. She developed this completely on her own, without any deliberate teaching from either of her parents.
And her behavior is not just a hedonistic calculation, either. If I give her anything, she insists that Thomas have an equal amount and then waits until he gets up from his nap to enjoy it with him. It's great to see that she is developing good habits at such a young age. I just have to make sure that I give her the chocolate in a cup so it doesn't melt all over her hands.