Originally published in slightly different form December 5, 2012 at PsychologyToday.com.
Bite-ables vs. Comestibles
In The Intelligence of Dogs (1994), Dr. Stanley Coren made the then-astounding claim that dogs have roughly the same linguistic skills as two-year-old children, an idea that has since gone mainstream.
After reading Dr. Coren's claim, I wondered if it were really true, so I set up a simple series of tests to see if my Dalmatian Freddie could distinguish between the names of his five favorite toys. Within about 20 minutes, he learned to differentiate pretty well, although he’d sometimes choose the empty Poland Spring water bottle (his favorite) when I'd cued him to take one of his other toys1.
A few days later I decided to test his ability to distinguish between five different types of food: a piece of chicken, a piece of cheese, a liver treat, a faux chocolate (carob) treat, and a biscuit. The olfactory bulb in dogs (which processes their sense of smell) is roughly forty times the size of that in humans (relative to each species’ brain size), so I thought it would be much easier for Freddie to differentiate between objects with different odors than toys. But no matter how slowly and carefully I tried to teach him the names of the edible objects, he couldn’t do it.
Clearly there are very sharp delineations between one type of food and another, perhaps more so than between one type of toy and another. So why the difference in Freddie’s performance?
I think it’s telling that in recent years two border collies, Rico and Chaser, have shown amazing “vocabulary” skills. Rico knew the names of over 200 of his toys. Chaser knew the names of over 1,000. But their vocabulary skills were limited to one type of object: something they could pick up with their teeth and carry around in their jaws.
Size & Texture (Mouth Feel) vs. Shape (Visual)
A new study may explain why Rico and Chaser’s language skills were centered specifically around bite-able objects, and perhaps why Freddie failed to recognize the names of food objects, but was easily able to differentiate between the names of his toys.
This study was done with another border collie named Gable, and it suggests that a dog’s brain may be designed to pay more attention to the size and texture of toys (how they feel between the dog’s teeth) than to their physical shape (how they look).
In their paper, “Word Generalization by a Dog (Canis familiaris): Is Shape Important?” Drs. Emile van der Zee, Helen Zulch, and Daniel Mills of the University of Lincoln (in England), write: “We taught the dog arbitrary object names (e.g. dax) for novel objects. Two experiments showed that when briefly familiarized with word-object mappings the dog did not generalize object names to object shape but to object size. A fourth experiment showed that when familiarized with a word-object mapping for a longer period of time the dog tended to generalize the word to objects with the same texture. These results show that the dog tested did not display human-like word comprehension, but word generalization and word reference development of a qualitatively different nature compared to humans.”
They go on to speculate that this difference may be due to evolutionary differences: for proto-humans the visual system was a primary source of information, implying that for dogs and wolves, “mouth feel” may have been more important.
Language Acquisition vs. Pattern Recognition
Like Dr. Coren, the teams of researchers who worked with Rico and Chaser claimed that each dog's ability to associate words with toys was comparable to the linguistic skills of a three-year-old child, ignoring the fact that the dogs' skills related to only one class of objects whereas toddlers have a much broader, wide-ranging grasp of vocabulary. Plus kids can use words to express their internal states. They can also use words related to simple concepts not just physical objects, they can differentiate between nouns and verbs, and they can use simple sentences and understand grammar, something even chimps can't do. Even 7-month old babies, when raised in a multi-lingual household, can differentiate between two different forms of grammar.
So while the abilities of these dogs are truly amazing, they have less to do with language acquisition than with pattern recognition, an evolutionary pre-cursor to language.
Still, why border collies? Why aren't other breeds as good at this?
Suppressing the Urge to Bite
Like all dogs, border collies are descended from wolves. And their predatory instincts have been shaped by humans to emphasize certain aspects of the wolf’s prey drive in order to perform specific types of work beneficial to our needs, while suppressing aspects that aren't as helpful. In border collies the desired aspects of the wolf’s prey drive relate to how wolves gaze at or stalk a herd of animals and then get them to move en masse. The most undesirable aspect is the urge to bite or kill the sheep, so those behaviors have been genetically suppressed.
Remember, the so-called linguistic abilities of Rico, Chaser and Gable relate to a specific class of objects: things they can bite, chew on or hold between their teeth. This suggests that their gifts of intelligence may actually be located in their teeth and jaws, not their brains!
However, if the urge to bite has been genetically suppressed in border collies, one might easily imagine that they would have very little interest in toys. Yet the opposite is true. Border collies can become obsessed with their toys. That’s because suppression doesn’t get rid of the urge to bite, it just "puts a lid on it," which can often increase its intensity.
What do I mean by this? Well, when a dog "works sheep" from dawn to dusk, she's putting in a very long hard day, and most of her drive energy gets used up with little left over for her chew toys. But for dogs raised as pets, the only way to use up anything close to that amount of energy is through some type of play, which usually involves something bite-able: a ball, a tug toy or a flying disc. (There's an old saying: "If you don't give your border collie a job she'll use her teeth to re-decorate your house.")
So what if we were to test border collies on their ability to memorize the names of objects unrelated to their urge to bite, for instance food items (as I tried with Freddie), or items of clothing, pieces of furniture, etc?2
Is the Urge to Bite Relevant to Learning?
Our current understanding of how learning takes place (or one of them) is that dopamine is released, either in connection with the establishment of a new pattern or a change in an expected one. This creates feelings of pleasure, ensuring that the animal repeats that specific behavior.
If we look at my two informal "studies” with Freddie, as well as those involving Rico, Chaser, and Gable, we can see that the urge to bite may be the most important factor in how dogs learn. If learning is about pattern recognition and dopamine-release, then dogs seemingly get more pleasure when they detect patterns while grasping things with their teeth than they do when detecting them visually. It may also mean that, at least for dogs like Freddie, there’s more pleasure to be had through biting a toy than there is through eating a favorite treat3.
I can’t say for sure, but this may be part of what motivated noted author and behavioral scientist Dr. Karen London to write recently, in The BARk Magazine, that the use of the term "prey drive" has become increasingly popular in recent years.
“When most people talk about prey drive in dogs,” says London, “they are referring to the enthusiasm and strong motivation that makes dogs sharp on the course, eager to participate and reliably give their all in competition or in play. I suspect that the term ‘prey drive’ is here to stay, and I sure hope that the joy of dogs who possess it also remains with us forever.”
Amen to that.
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1) The chewable objects I used were a rawhide, a tennis ball, an empty Poland Spring water bottle (his favorite), a plush chew toy, and a rubber chew toy. To make it harder, I gave them similar sounding names: “boney,” “bally,” “bottie,” “baby,” and “birdy.”
I showed Fred each of them in turn, referring to them as “boney,” “bally,” “bottie,” “bitey,” and “birdie,” and let him take each one in his mouth as I repeated their names. I deliberately used words that sounded somewhat similar to see if Freddie had the ability to distinguish between them despite their similarities, just as children do. Then I told Fred, “Get the boney,” (etc.) and gave him each object in turn, repeating their names. The next step was to say the name of an object, and tell Freddie to “get it!” I tested him each day, for short periods of time, and after about a week, he got pretty good at it.
The edible objects were a piece of chicken, a piece of cheese, a liver treat, a faux chocolate (carob) treat, and a chewable biscuit. I called these objects “chicko,” “cheddar,” “chiver,” “chocko,” and “chomsky” (after linguist Noam Chomsky).
2) Another thing to consider is the difference between cats and dogs. Housecats are very clever animals; in some ways, they’re much smarter than dogs. Is it possible to train a cat to remember the name of its chew toys? Of course not. Dogs like chew toys while cats prefer the kind they can swat at with their paws. Besides, while cats have hunting instincts, their prey drive—the ability to sustain that set of hunting instincts over a period of time—is nowhere near as strong as a dog’s. (A cat might, on its own, find it fun to try to herd a flock of sheep for a few minutes, but it could never perform the task for hours on end as border collies do.)
3) I’m not against using food in training. It’s a very useful tool, particularly as a means of “breaking the ice” with a dog, establishing a social connection, and for its calming effect.
However, as positive trainer and blogger Eric Brad noted recently, food rewards can sometimes have a negative impact on learning because they distract the dog from focusing on the desired behavior; all the dog can "think" about is getting that reward. This is exactly what happened when I tried to teach Freddie the names of his favorite treats. He had no interest in learning them; he just wanted to eat them.