And that is exactly what happened. As reported in the April issue of the journal Psychological Science, the dogs that exerted self-control and then got replenished with sugar performed just like the dogs that had not been exhausted to begin with. They persisted with the Tug-a-Jug, even though it was frustrating and demanding to do so. The depleted dogs that had not received the sugar drink gave up much more quickly. In short, all the dogs acted the way that humans do in similar situations requiring restraint and goal-directed activity.
So perhaps humans are not unique—at least not in this regard. It appears that the hallmark sense of human identity—our selfhood—is not a prerequisite for self-discipline. Whatever it is that makes us go to the gym and save for college is fueled by the same brain mechanisms that enable our hounds to sacrifice their own impulses and obey.
This article was originally published with the title Dog Tired.