The article I was reading talked about another aspect of the test involving the environment and past experiences, but that's not important. What is important is that they pointed out this was one of the funniest experiments to watch because the kids were so hilarious in their attempts to not eat the marshmallow.
Need proof? I present to you a video of kids doing the Marshmallow Test.
My favorite is the little girl who by the time the researcher says "two" has that marshmallow stuffed in her mouth. :D