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Dogs Offer Clues to Self-Control

Experiments on canines suggest self-control, in both humans and animals, is related to blood glucose levels.
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"Why can’t you exercise self-control?” That disdainful question has been posed repeatedly to procrastinators, overeaters and others who find it hard to resist self-destructive impulses. It has rarely, if ever, been asked of dogs.

But according to newly published research, the same mechanism that regulates human self-control also operates in canines.

The study, in the journal Psychological Science, confirms the notion that self-control is a limited resource, one that can and does get depleted. It also suggests this is not “a uniquely human process.”

A University of Kentucky research team led by psychologist Holly Miller conducted two experiments with groups of canines, observing how much persistence they exhibited when given a task. The first experiment featured 13 dogs (two Belgian Tervurens, four Australian shepherds, a Hungarian Vizsla and four mutts) who had been trained to sit and stay at their owners' command.

The dogs were separated into pairs based on their training history. One from each pair was cued to sit and stay by its owner for a total of 10 minutes, with the command being repeated as necessary. The other was simply kept in a quiet room for that same amount of time.

Afterward, each dog was given a Tug-a-Jug toy, a clear cylinder containing treats that can be accessed via a hole at one end — if the dog manipulates it properly. Each toy contained a small wooden block and half a wiener, which the dogs very much wanted to get at. Alas, they were unobtainable, being too large to fit through the hole.

The dogs that had exercised self-control by sitting in place for 10 minutes gave up and discarded the toy more quickly than the others. They “appeared to have depleted some important resource, which led to decreased persistence on the unsolvable task,” the researchers write.

Interesting, in a Samuel Beckett meets Animal Planet sort of way, but can this canine behavior really be equated with the human willpower? In a follow-up interview, Miller noted that a human exercises self-control when he or she ignores temptations and distractions, and completes a project, be it filing a report or taking out the trash.

“In the case of the dogs, they too were trained to work on a project (the Tug-A-Jug toy),” she notes. “And when the project became difficult and non-rewarding, they faced a trade-off: Should they persist on the difficult project in order to obtain the reward? Or should they give up trying?

“The dogs that were depleted were unwilling to persist for long with their goal-directed behavior, but the dogs that were not depleted were able to persist longer.”

A second experiment, on 22 dogs of various breeds, repeated the first with an additional component: Half the dogs in each condition were given a glucose drink prior to grappling with the toy, and half were given a sugar-free beverage. Previous research has linked self-control in humans to blood glucose levels.

“Dogs given a glucose drink persisted in interacting with the toy whether or not they had had to exert self-control prior to the test,” the researchers report, adding the glucose apparently replenished the animal’s capacity to keep at the task.

Miller appreciates the irony in this finding, which suggests the way to replenish one’s self-control (say, to resist junk food) is to drink a sugary beverage. But she hastened to add she’s not recommending a trip to the soda aisle of 7-Eleven.

“All carbohydrates, once digested, are converted into glucose,” she said. “Some carbohydrates are digested quickly and have immediate effects (e.g. a glucose drink). Some are digested more slowly and have a longer lasting effect (e.g. apples).

“If I were translating this into the recipe for a good weight-loss intervention, I would advise people to eat when they are hungry and always choose foods that are low on the glycemic index. These foods will provide the brain with energy for longer durations of time and thus fuel the ability to inhibit eating unhealthy foods.”

So these experiments on dogs contain an interesting implication for humans: Willpower — presumably a foreign concept to canines – isn’t so much a question of character as it is one of biology.

“People can control their own behavior,” Miller said. “When they fail, it is not because they are terrible or weak; it is because they are depleted.

“They need to evaluate what they are eating in order to determine if they are eating wholesome food at regular intervals. And if they want better self-control, they can build it. They can encourage their bodies to store more self-control fuel via exercise.”

So, to conserve the fuel crucial to making smart choices, go out for a run. Better yet, take your dog.

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