Self-Control is Not Just a Human Trait

Common is the idea that only humans, with our abilities to reason and delay gratification, are able to display self-control, thus setting us apart from the animal kingdom.  Yet, a recent study suggests that other species may have similar powers of control.

Researchers from the University of Kentucky hypothesized that self-control is not a uniquely human trait.  Basing their logic on the documented theory that the brain’s “executive” powers, which control thought and action, are a form of cognitive processing that is fueled by glucose, they suggested that depletion of the brain’s glucose stores may lessen the brain’s ability to self-discipline.  Looking at self-control as a biological function that is most likely present in most, if not all, mammals, a research team led by scientist Holly Miller attempted to determine if dogs, too, could exercise powers of self-control under the right circumstances.

Using dogs ranging in age from 10 months to 10 years, Miller and her colleagues utilized a dog toy called a Tug-a-Jug, with which all of the study dogs were familiar.  The toy is a clear contraption that holds dog treats, and dogs learn to easily manipulate the Tug-a-Jug until it yields a treat.  In the study, the dogs were put into one of two groups.  The first group of dogs was ordered to “sit” and “stay” for 10 minutes, which was considered a stress-inducing exercise that would deplete the dogs’ glucose stores.  The second group was the control group, and these dogs were merely required to sit in a cage for 10 minutes, which was not expected to deplete glucose stores in any notable way.

At the end of the 10 minutes, both groups were offered the clear, cylindrical Tug-a-Jug toy, full of dog treats.  Each Tug-a-Jug was rigged so that the dogs were not able to access the treats, and their treat-seeking behavior was closely monitored.  The group of dogs that was mentally exhausted from sitting for 10 minutes on orders gave up on the hope of getting a treat from the jug after only one minute.  The control group reliably gave two minutes or more to the effort of retrieving a dog treat; they had substantially more endurance than the group that had been ordered to obey for 10 minutes.

To test the theory of glucose-powered self-control, Miller and her team replicated the study, allowing some of the dogs that obediently sat still for 10 minutes to have a drink of a sugar-sweetened liquid, while others in the group received an artificially sweetened drink.  The idea was to test the theory that the sugar would refuel the obedient dogs’ depleted stores of glucose, thus reviving their executive powers.

Indeed, the dogs that received the sugar-laden drink after a stress-inducing 10 minutes of obedience demonstrated as much resolve to retrieve a treat from the Tug-a-Jug as did the dogs in the control group that merely sat for 10 minutes.  Naturally, the dogs that were refueled with an artificially sweetened drink gave up quickly on the treat toy when it was clear that it would not readily yield a snack.

The study researchers conclude from their findings that self-discipline is less the hallmark of human identity that it was previously thought to be, and more the function of basic biology common to all of man and animal-kind.