The Stanford Marshmallow study is a seminal study in the science of self-control and delayed gratification conducted by Mischel in the 60s and 70s. In Mischel's experiment, children could choose from a small immediate reward (one marshmallow) or, if they waited for fifteen minutes, they could get a larger reward (two marshmallows). Follow up studies showed that students who chose the larger reward later, that is, who were able to delay gratification, were, in general, more successful in life.
This study initiated a number of subsequent studies in the areas of delayed gratification and self-control.
Now you know why you are getting marshmallows! After every (unburnt) marshmallow you receive, celebrate!