Science & History
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We talk with Alexandra Horowitz, assistant professor of psychology at Barnard College, about her new book, Inside of a Dog: What Dogs See, Smell, and Know. This engrossing work is inspired by Horowitz’s experiences with her dog, Pumpernickel, and draws upon her own and others’ research in the field of canine cognition. This book expands our understanding of the nature of dogs and provides a channel to seeing and “smelling” the world from a dog’s point of view.
Bark: Your fascinating new book, Inside of a Dog, begins with a discussion of canine “umwelt.” Can you tell us more about umwelt and how it might affect our understanding of our dogs?
Alexandra Horowitz: The idea of umwelt, which originated with the biologist Jakob von Uexküll, is that the world of each animal is defined by how he/she perceives and acts on the world. Thus, the umwelt of humans does not include infrared light, since we have no perception of these wavelengths and cannot act based on seeing it. However, for bees, who can see infrared light, it is part of their umwelt, and they use the reflected infrared from the center of some flowers to locate nectar. The scale of objects, and their salience, also matters. In our ordinary life, we humans don’t deal on [what we call] the microscopic scale of bacteria: thus, objects that small aren’t part of our impression of “what is out there” at all. A dog’s umwelt is determined by what he can perceive, by his history, by what matters in the world to him. Humans are clearly a big part of the umwelten of dogs, but we don’t register much in the fly’s umwelt (at least, not as anything distinct from other mammals).
For dogs, we can imagine that their world is defined by their perception and action. Their perception includes being able to smell much more acutely than we can (including detecting changes in others’ hormones) and hearing within a greater range than we can. Thus, they will be able to respond to stimuli we don’t even notice. At another level, their umwelt is defined by the things they can bodily act on: They handle the world with their mouths, so the world gets divided into things-that-fit-in-the-mouth and things-that-don’t-fit-in-the-mouth—a way of seeing the world that is quite different than our own.
If we begin to understand what dogs think about, what they can see and smell (and what they can’t), I think we’ll have a better understanding of what it’s like to be a dog—the dog’s perspective, if you will. Appreciating his perspective goes a long way toward making a closer relationship (as it does between people!).
B: The dog’s amazing olfactory powers make their worldview different than ours. Can you explain why?
AH: As we go about our day, we see the world first, using vision to help make sense of the sounds (conversation, sudden honking, a nearby thud) and the smells (something rancid or sweet wafting on the air) around us. Dogs smell the world first, using olfaction to organize and make sense of what they see and hear. The richness of our visual world is matched, if not surpassed, by the richness of their olfactory world.
This leads to some profound differences in the way the world looks, which I describe at length in the book. For instance, smells deteriorate over long distances, and are carried hither and thither by currents of air. The visual scene does not change with the breeze, and with distance, only looks “more distant.” The result is that the world is mapped differently for the creature who primarily “sees” it via his nose rather than his eyes.
B: You note that dogs couldn’t really see TV in the pre-digital conversion days; the physiological reason behind this is significant—can you explain it?
AH: It has to do with how we process light. Specialized cells in the eyes of mammals translate light waves into neural activity by changing the pigment in the cells. In the milliseconds that the pigment is changing, the cell can’t receive any more light. This leads to what is called the “flicker-fusion” rate: essentially, the number of snapshots of the world that the eyes can process each second. Our flicker-fusion rate is about 60 images per second.
The image on old TVs and film is really a sequence of still shots sent quickly enough to fool our eyes into seeing a continuous stream. Given our flicker-fusion rate, the film needs to be only slightly faster than 60 still images a second to trick our eyes into seeing motion. Dogs, though, have a faster flicker-fusion rate—about 70 or 80 stills per second. When watching film, they can actually detect the individual frames as well as the dark spaces between them. With the recent conversion to entirely digital television broadcasts, though, the flicker-fusion rate is no longer relevant, since digital TV works differently. So dogs can, in theory, watch TV—though it still is not very olfactorily interesting!
B: Why do you think it took researchers so long to truly study the dog?
AH: I think it took scientists a long time to see dogs as cognitively interesting because they reasoned that animals who are closely related to us—like apes and monkeys—were more likely to display behaviors similar to those of humans. As it turns out, in social cognitive tasks such as interpreting others’ gestures, dogs often surpass chimpanzees in performance! Additionally, I suspect that it was felt that dogs were already “known,” because they are so common and familiar to us as pets. What we are discovering is that in some cases, we are correct about what dogs know and understand, and in many cases, our common-sense understanding of dogs is not quite right.
B: A lot of your research involves dog play. Why is play so important?
AH: Play is a terrific venue in which to see dogs’ fast-paced, coordinated behavior; they are highly skilled players. As many dog owners may know, most bouts of play begin with a play signal, such as the familiar “play bow,” in which one dog bends down on his front legs, holding his rump high and his tail up and wagging. Another signal is the “exaggerated approach,” in which one dog lopes toward another dog, often with an extra-bouncy stride. These signals are considered requests to play, or announcements of an interest in playing. It appears to be important to play signal before starting to play, since play involves behavior that would be considered aggressive—biting, mounting, bumping—in another context.
When I looked at play sequences in very slow motion, what I was able to see was that dogs were very good at getting the attention of their hoped-for playmates before play signaling. And they seemed to know what kind of attention-getter would work in different situations: a more forceful attention-getter when the other dog is distracted, a mild one when the dog is standing idly. With humans, a person might need to shout to get the attention of someone talking to someone else; similarly, we don’t need to barge into someone standing right in front of us in order to get his attention. Dogs seem to know that. And then, only after getting the other dogs’ attention, did they signal an interest in playing.
B: Dogs of the same “breed type,” like herders, seem to enjoy playing together and appear to have different styles of play than other breed types. For instance, they use the “eye,” and play “who winks first gets to be chased.” Have you studied behavioral traits in breeds and how they are expressed during play?
AH: I find it extremely interesting that breeds often gravitate to other members of their breed to play. Indeed, it seems that even similar-looking mixed-breeds often play together. Some of that could be explained by their owners’ interest in the familiar-looking or -acting dog (if owners loiter together, it gives the dogs more time to get acquainted). But most of it presumably comes from the dogs’ mutual recognition of characteristic behaviors in one another: the way the other dog solicits play, how he uses his tail and, as you suggest, even showing “eye” or other breed-typical behaviors. My own research did not control for breed, and I don’t know of any other studies that have specifically identified whether or not certain behaviors are more likely during play among members of one breed than play among members of another. It’s ripe for the investigating!
B: It was interesting that you said that long-time or close playmates can exchange shorthand signals with each other. How can we learn to read our dog’s shorthand?
AH: The shorthand is usually a component of the play signal. The play bow involves bringing the forelegs down and the rump up—so, a shorthand version of that is what I call a “play slap”: just bending down on the front legs, usually with an audible slap. Similarly, many signals involve an open, almost grinning-looking mouth; as shorthand, a dog can do a very short open-mouth display with another dog. If you know the components of the signals, you can see how dogs break them up to use with their regular playmates.
B: In regard to your statement that dogs don’t hunt cooperatively—since dogs evolved from wolves, who do hunt cooperatively, it would seem that dogs would, too.
AH: You make a great point. Some dogs may hunt together—and dogs definitely act cooperatively with each other in many settings, including play. My point is a little different, however. What I wanted to emphasize was that typical dog behavior has changed considerably from typical wolf behavior in numerous ways. The studies on which I base my statement were on free-ranging (stray) dogs who need to hunt or scavenge to eat; researchers found that the dogs did not hunt together cooperatively, as we see in wolves. These groups are perhaps the closest model that we have of what is natural social behavior for dogs unmodified by the immediate presence of humans. Dogs bred for hunting may also act very differently, of course, than mixed breeds.
B: Pointers can “honor” the point of another dog while hunting—a truly amazing thing to see. Mark Neff at UC Davis is collecting evidence of the genetic basis of this behavior. Are you familiar with this behavior?
AH: Following another dog’s hunting point is very consistent with all the recent experimental research showing that dogs are quite good at following dogs and humans who indicate (by pointing or looking) where a hidden toy or food is. This may seem obvious to some dog owners, but to psychologists, it is quite meaningful that dogs follow points; most non-human animals don’t seem to use pointing as an informational cue. It is also a testament to the quality of the experiments that we see this ability in the dogs’ natural lives as well.
B: I was happy that you discussed dogs’ fascination for novel objects (neophilia). But have there been any studies that actually showed this to be true?
AH: Yes. In 2008, Kaulfuss and Mills published a study showing neophilia in dogs. The dogs in their study were given the choice of new or familiar toys, and most preferred the new toys. This doesn’t mean they will always be interested in a new toy; rather, it indicates that dogs have a sense of what is familiar and what is novel, and are curious enough to investigate the novel.
B: How can you tell if your dog feels or is expressing guilt?
AH: It is an open question whether dogs feel guilt, one that we all have our hunches about but that is very hard to confirm empirically. I recently published a study testing whether the “guilty look” that dogs show—ears back, tail down, slinking off or avoiding eye contact—actually indicates that the dog has disobeyed and possibly feels guilty. I found that dogs showed the most guilty look not when they had actually disobeyed, but rather, when they were scolded or confronted by a suspicious owner, even if they had done nothing wrong.
What most dogs do seem to know is that some actions—those that have provoked punishment in the past—are “wrong,” off-limits or at least likely to provoke punishment again. This is not the same as feeling guilt. They may do the guilty look as an entreaty not to be punished.
B: How can you tell if your dog is bored? I know that is one of the biggest concerns of dog lovers.
AH: Boredom in dogs looks remarkably similar, in broad strokes, to what it looks like in humans: flagging energy, reduced activity, poor attention, sleeping too much. Dogs may pace (similar to zoo animals kept in too-small enclosures with nothing to engage them) or do repetitive actions, such as licking or chewing themselves obsessively. If you come home to find your house in disarray, socks mauled, pillows disemboweled, it’s likely that your dog was bored—at least until he found those socks and pillows with which to occupy his time. Boredom can be sated by giving the dog something to do: play with him, give him plenty of social time with other dogs, or hide safe toys or treats for him to find when you’re away.
B: You said that “in many ways, dogs act as if they think about their memories as the personal story of their life.” What do you mean by this?
AH: It is an intriguing question whether dogs think about themselves—that is, whether they have a sense of their own life story, their autobiography. It is also a very difficult question to address scientifically. I am proposing, however, that much of dogs’ behavior, such as what they remember—where they buried that bone last summer, the dog who was hostile the last time they met, a shortcut home—indicates that they are in fact thinking about their life in an autobiographical way.
B: A final question. Is there a possibility that dogs co-evolved with us, especially since the dog genome dates the wolf/dog split to almost 100,000 years ago, about the same period during which Homo sapiens was developing? Also, the change “out of wolf” began so long ago that it would seem to predate human settlements. So perhaps the theory of dogs “taming” themselves as scavengers around our “settlements” might not be right.
AH: I think it is quite appropriate, based on the evidence we have, to say that dogs and humans co-evolved. As I discuss in the book, there is archeological evidence that dates the intertwining of our lives to 10,000 to 14,000 years ago, though most researchers believe that we lived together for perhaps thousands of years before that time. The interesting and more recent finding (using mitochondrial DNA)—that wolves split into two different groups, one of which was to become what we now know as the domestic dog—is suggestive that the connection between humans and dogs may have been quite long ago. It is also possible that these “proto-dogs” were well suited to later domestication, but weren’t yet associating with humans (or our forebears). The evidence simply isn’t all in yet.
To listen to an interview with Alexandra Horowitz on NPR, click here .
Photo courtesy of the author.