Dog Sense (35 page)

Interestingly, however, the dogs weren't incapable of understanding where the ball had gone. They
did
get the right answer when the ball was moved from one screen to another by an invisible string rather than by a person. Evidently, their first priority was always to do what a human had encouraged them to do in the past. Even hand-raised wolves maintain a sufficient degree of independence from people to keep their minds on the problem as presented to them; dogs are just too easily distracted, too eager to please a human.

Just because they can follow a human's gaze or hand gesture doesn't necessarily mean that dogs understand what that person is thinking. They might simply be using the person's eyes as a convenient but otherwise arbitrary pointer as to what they should attend to next. Two remarkable studies done in France
¹⁴
have exposed some of the dog's limitations. Detailed comparisons were made between guide dogs, owned by blind people for several years, and ordinary pet dogs living with sighted owners. First, the researcher studied how the dogs tried to get food from their owners. They all used the standard doggie routine of looking forlornly at their owner, then at their bowl, and then back again:
The guide dogs gave no indication that they knew their owners were blind.
The only difference was that the guide dogs made louder slurping noises, which their blind owners could and did attend to. This tactic can be accounted for by simple associative learning—the dogs had learned that food followed when they made the noises—and doesn't prove that the dogs understood anything about blindness. Next, the study examined how dogs draw the attention of their owners when they are trying to get at a toy made inaccessible behind a heavy wooden box. Here, too, the pantomime of looking back and forth between the owner and the toy went on, irrespective of whether the owner could see it or not. Other scenarios produced similar results, such as the owner offering the dog a different toy instead of the one it wanted: Again, no difference. There was no indication that the guide dogs knew that their owners were blind and that they thus had to rely on other cues, such as sounds, to tell them which way to point their heads.

These experiments tell us that dogs have a passion for following human gaze, but they do not tell us whether they are born with this obsession, or whether they learn it. The guide dogs that were studied had not always lived with blind people; they had been raised by sighted families for the first twelve to eighteen months of their lives, before starting guide-dog training. Perhaps these are the critical years in which the habit of following a person's gaze is learned, after which it is very difficult to unlearn. However, it is remarkable that the guide dogs seemed hardly to have altered their behavior at all in the four years, on average, that they had been living with a blind person.

This apparent overreliance on human eyes and arms raises the question of whether dogs actually have the ability to understand what we're
thinking. They are clearly responsive to what they see us
doing
, but that's not the same as understanding that each human has a mind—one that, furthermore, is different from their own. Such an idea must seem like heresy to the majority of dog owners, but science has thus far failed to demonstrate such abilities in
any
species apart from our own. Even the many experiments that have been done on chimpanzees have failed to provide conclusive evidence that the great apes know other minds exist.

Part of the problem is that it is very difficult to design experiments that test whether dogs are able to tell what we're thinking—in other words, experiments that exclude simpler explanations for their behavior. For example, in a study examining whether dogs understand what people can and can't see,
¹⁵
eleven dogs that had been trained not to steal food were taken into a room where there was a piece of food on the floor. When the experimenter told the dogs not to eat the food when she was facing them, they usually left it, but when she was faced away from them while issuing the command, they often did take the food. The dogs might have “known” that they couldn't be seen, but the simpler explanation is that they associated seeing a human face with obeying a command—“If the face is not there, then the verbal command doesn't mean anything.” Given that dogs are so sensitive to human faces and the expressions on them, it's very difficult to design experiments that would rule out such an explanation.

However, a subsequent experiment showed that not all dogs are equally sensitive to being watched.
¹⁶
In this instance, dogs were invited to take food from behind barriers of various shapes and sizes. One barrier, for example, hid the food but allowed the dog to see the experimenter when she was approaching the food; another was larger but with a small window, blocking the dogs' view of the experimenter until the dogs were very close to the food. A few of the dogs behaved as if they understood which barriers blocked the experimenter's view of the food and which didn't. Others seemed much more inhibited if she could see them start moving toward the food but were oblivious to the fact that they could actually be seen eating it (e.g., through the window in the barrier). Thus it is still not clear whether dogs can work out what people can and can't see, or whether they're responding to simple learned “rules” such as “If I
can see a person's face, then I shouldn't move toward food” or “If I can see a person's face, then it's OK to move but I mustn't actually eat.”

Such experiments show that dogs are very sensitive to whether people are watching them or not. They do not, however, provide conclusive evidence that dogs know what people are
thinking
—that they possess what cognitive biologists refer to as a “theory of mind.” Most dogs have been fed all their lives from a bowl placed on the floor by a person's hand, so it's hardly surprising that they like to follow the direction that a human hand is pointing to or moving in. Moreover, most dogs have learned that the way a person reacts to them will be quite well predicted by the direction in which the person is facing and moving. Consciously or not, humans
expect
dogs to be very sensitive to our body-language. This capacity must have been so useful to cementing the bond between man and dog that any dogs who lacked it were probably selected out of the population many, many generations ago.

Further evidence that dogs do not possess a “theory of mind” lies in their susceptibility to deception. In one recent experiment, dogs were trained to expect that one person (the “truth-teller”) would always point at a container with food in it and that another (the “liar”) would always point at an otherwise identical but empty container.
¹⁷
More often than not the dogs preferred to go where the truth-teller pointed, but by no means every time. When the people were replaced by a simple association that a white box always contains food (truth) while a black box never does (lie), the dogs marginally preferred the white, “truthful” box. Thus there was no evidence that the dogs had understood the difference between truthful and untruthful people; more likely, they had just learned to associate one of the people with getting food.

In sum, domestication does not seem to have given dogs the ability to read our minds, or even to understand that humans are capable of independent thought. They must therefore live in a subjective world that is very different from ours, one in which we exist not as independent entities but merely as components of that world (albeit usually the most important components). This is actually unsurprising, given what we now know evolution is capable of. The dog is stuck with a canid brain—and although this has undoubtedly been modified by domestication, it is
asking too much to assume that a whole new layer of complexity could have been added during the domestication process.

So if dogs don't know what we're thinking, how come they give the impression that they do? From almost as soon as they can see, dogs seem to be especially sensitive to actions performed by humans. This difference from the wolf is almost certainly due to a genetically programmed change of focus in the dog's priorities, driven by domestication. Those proto-dogs that happened to possess a predisposition to attend to the humans around them would have been able to learn the significance of specific human gestures. This adaptation, in turn, would give these more sensitive dogs a key advantage over more wolf-like dogs who would have been more focused on their own species and the physical world.

Today, this almost overwhelming focus on people and what they are doing enables dogs to learn very subtle aspects of human body-language, possibly even actions that we are unaware of ourselves. In addition, they almost certainly gather information about us, using their hypersensitive noses, based on subtle changes in odor that we are entirely unaware of. (This capacity to recognize subtle changes in body odor very likely lies behind the ability of trained dogs to detect impending seizures in diabetics and epileptics.) It is the shift in the focus of attention—from other members of their own species to members of the human race—that is domestication's primary effect on dogs' intellect. There has been no step-change in overall ability, just an adjustment of their primary focus. Dogs appear to be no more or less limited than wolves in terms of what they can learn; it's just that the priorities of what to learn and who to observe have been changed by domestication. Thus, although dogs appear to understand what we are thinking, no evidence has yet been found that suggests they are aware that we even
can
think. They are merely very well adapted to respond in the most productive way, nine times out of ten. Give them a situation that evolution has not prepared them for, such as an owner who is blind, and they continue to adhere to the standard ways of responding to people.

The dog's apparent lack of a “theory of mind,” then, raises the question as to whether dogs even have distinct concepts for “a person” and “a
dog.” The level of attachment between dog and owner is different from that between dog and dog, but is there also a qualitative difference? Dogs obviously behave differently toward people than toward other dogs, but could this simply be a consequence of one species walking upright and the other on all fours?

Play behavior should be a useful window into this aspect of the dog's mind, since it incorporates a kind of “lingua franca” that dogs and people can use to communicate their intentions equally well. Dogs can of course be readily persuaded to play with other dogs as well as with people, and human volunteers can be persuaded to play as if they were dogs—for example, by staying on all fours throughout the game. Together with my colleagues at Bristol University, I've been making comparisons between dog-dog play and dog-human play in order to gain insight into whether dogs play differently depending on which species they're playing with and, by inference, whether they have different mental concepts of “person” and “dog.”
¹⁸
We recruited a dozen Labrador retrievers, all chosen on the basis of their reputation for being particularly playful, as well as for being a popular breed. The dogs were released, one at a time, into a large grass paddock accompanied either by another dog (one it knew well) or by one of its regular carers. We gave the dogs two minutes for an initial exploration of the area and then threw into the paddock a tug-toy consisting of a short length of knotted rope. All the dogs were accustomed to and enjoyed playing tug-of-war games and thus immediately began playing with the rope, regardless of whether their play-partner was another dog or a person.

The dogs spent most of their time engaged in the game—again, regardless of whether they were playing with a person or with another dog. On the other hand, they clearly played very differently depending on who their partner was. When playing with the person, the dogs were much more likely to surrender the toy, seemingly in order to keep the game going. But when two dogs were playing, each tried to keep possession of the rope, attempting to guard it from the other whenever the other let go.

This behavioral distinction was even more pronounced when we added another component to the game. Three minutes after the first tug-toy was thrown into the paddock, we threw in a second one. Now each
dog had the choice of continuing to play with the original toy or grabbing the second toy and going off to play with it on its own. Here, the difference between the way dogs played with humans and the way they played with other dogs was dramatic. When two dogs were play-partners, they would often each take a toy and play with it for a while on their own before coming back to play together again. But when the play-partner was a person, the fact that there was a second toy available seemed almost irrelevant: The dog kept on bringing one toy back to the person and inviting her to keep on tugging.