Inside of a Dog: What Dogs See, Smell, and Know

by Alexandra Horowitz

dogs experience a color most strongly when it is in the range of blue or green.

In all mammalian eyes, rods and cones make electrical activity out of light waves by means of a change in the pigment in the cells. The change takes time—a very small amount of time. But in that time, a cell processing light from the world cannot receive more light to process. The rate at which the cells do this leads to what is called the “flicker-fusion” rate: the number of snapshots of the world that the eyes take in every second.

To create a simulacrum of reality, films—literally “moving pictures”—must exceed our flicker-fusion rate only slightly.

fluorescent lights are so annoying because they operate too close to the human flicker-fusion rate.

Dogs also have a higher flicker-fusion rate than humans do: seventy or even eighty cycles per second. This provides an indication why dogs have not taken up a particular foible of persons: our constant gawking at the television screen. Like film, the image on your (non-digital) TV is really a sequence of still shots sent quickly enough to fool our eyes into seeing a continuous stream. But it’s not fast enough for dog vision. They see the individual frames and the dark space between them too, as though stroboscopically. This—and the lack of concurrent odors wafting out of the television—might explain why most dogs cannot be planted in front of the television to engage them. It doesn’t look real.

One could say that dogs see the world faster than we do, but what they really do is see just a bit more world in every second.

dogs can see some of the same things we do, but they don’t see in the way that we do. The very construction of their visual capacity explains a broad swath of dog behavior. First, with a wide visual field, they see what is around them well, but what is right in front of them less well. Their own paws are probably not in terrific focus to dogs. What wonder then how little they use their paws, relative to our reliance on the end of our forelimbs, to manipulate the world. A small change in vision leads to less reaching, grabbing, and handling.

The optic nerve, the neural route conveying information from the retinal cells to brain cells, tunnels right through the retina on its way back to the brain. Thus if we hold our eyes still, there is a part of the scene in front of us that is not captured on our retina—as there is no retina there to capture it. It’s a blind spot. We never notice this gaping hole in front of us because our imaginations fill in that spot with what we expect to be there. Our eyes dart back and forth constantly and unconsciously—movement called saccades—to further complete the visual scene.

The conversion to entirely digital television broadcasts will eliminate the flicker-fusion problem, making TV-viewing more viable (but no more olfactorily interesting) for dogs—who are no doubt ambivalent.

There is a powerful pull to a dog who looks you in the eyes. I am on her radar: it feels that she is looking not just at me, but to—and into—me.

We attend to others’ attention because it helps to predict what that someone other will do next, or what he can see and what he might know. One of the deficits that many people with autism have is an inability, or lack of inclination, to look at other people’s eyes. As a result, they aren’t instinctively able to understand when other people are paying attention—or how to manipulate others’ attention.

In experimental settings mining the same four elements of dog, experimenter, food, and knowledge, dogs seem to distinguish between humans who might be helpful to them and humans who will likely not. When a person with a sandwich is either blindfolded or facing away, dogs suppress the urge to stay as close as possible to the sandwich. Instead, if there is a nonblindfolded person nearby, they go beg to him instead. Let this be a lesson that begging at the table is probably encouraged by your eye contact toward the dog—even just long enough to tell him no begging! Alternately, set up one person as the responsive, looking beggee and all the dog’s attention will go to him. (Children are good for this role.)

Researchers have found that dogs not only understand when we are attentive, but are sensitive to what they can get away with at different levels of their owners’ attention.

dogs pick up on our hormonal levels in interaction with them. Looking at owners and dogs participating in agility trials, the researchers found a correlation between two hormones: the men’s testosterone levels, and the dogs’ cortisol levels. Cortisol is a stress hormone—useful for mobilizing your response to, say, flee from that ravenous lion—but also produced in conditions that are more psychologically than mortally urgent. Increases in the level of the hormone testosterone accompany many potent elements of behavior: sex drive, aggression, dominance displays. The higher the men’s pre-agility-competition hormonal levels, the higher the increase in the level of stress in the dogs (if the team lost). In a sense, the dogs somehow knew that their owner’s hormonal level was high, by observing behavior or through scent or both—and they “caught” the emotion themselves. In another study, dogs’ cortisol levels revealed that they were even sensitive to the style of play of human playmates. Those dogs playing with people who used commands during play—telling the dog to sit, lie down, or listen—wound up with higher postplay cortisol levels; those playing with people who played more freely and with enthusiasm had lower cortisol at play’s end. Dogs know, and are infected by, our intent, even in play.

By standard intelligence tests, the dogs have failed at the puzzle. I believe, by contrast, that they have succeeded magnificently. They have applied a novel tool to the task. We are that tool. Dogs have learned this—and they see us as fine general-purpose tools, too: useful for protection, acquiring food, providing companionship. We solve the puzzles of closed doors and empty water dishes. In the folk psychology of dogs, we humans are brilliant enough to extract hopelessly tangled leashes from around trees; we can magically transport them to higher or lower heights as needed; we can conjure up an endless bounty of foodstuffs and things to chew. How savvy we are in dogs’ eyes! It’s a clever strategy to turn to us after all. The question of the cognitive abilities of dogs is thereby transformed: dogs are terrific at using humans to solve problems, but not as good at solving problems when we’re not around.

One reason why as adults we don’t have many—arguably any—true memories of life before our third birthdays is that we were not skilled language users at the time, able to frame, ponder, and store away our experiences. It might be the case that while we can have physical, bodily memories of events, people, even thoughts and moods, what we mean by “memories” is something facilitated only by the advent of linguistic competence.

a claim about the dog’s knowledge of his misdeed is importantly off the mark. The dog may not think of the behavior as bad. The guilty look is very similar to the look of fear and to submissive behaviors. It is no surprise, then, to find so many dog owners who are frustrated with attempts to punish a dog for bad behavior. What the dog clearly knows is to anticipate punishment when the owner appears wearing a look of displeasure. What the dog does not know is that he is guilty. He just knows to look out for you.

dogs are quite capable of concealing behavior, acting to deflect attention from their true motives. Given what we know about their understanding of mind, it is entirely within their reach to deceive. And given that it is a rudimentary understanding, their deception is not always very good.

Every dog that you name and bring home will also die. This inescapable, dreadful fact is part of our lot for introducing dogs into our lives. What is less certain is whether our dogs themselves have any inkling of their own mortality.

Dogs certainly have the potential, with training, to be rescuers. Even the untrained dog may come to your aid—but without knowing exactly what to do. Their success is due instead to what they do know: that something has happened to you, which makes them anxious. If they express that anxiety in a way that attracts other people—people with an understanding of emergencies—to the scene, or allows you leverage out of a hole in the ice, great.

dogs like greeting us at eye level,

While Americans balk at strangers standing closer than eighteen inches, American dogs’ personal space is approximately zero to one inches.

The dog defines the world by the ways that he can act on the world. In this scheme, things are grouped by how they are manipulated (chewed, eaten, moved, sat upon, rolled in). A ball, a pen, a teddy bear, and a shoe are equivalent: all are objects that one can get one’s mouth around. Likewise, some things—brushes, towels, other dogs—act on them.

Moving things are more interesting than still ones—as befits an animal at one time designed to chase moving prey. (Dogs will stalk motionless squirrels and birds, of course, once they have learned that they often spontaneously become squirrels running and birds on the wing.) Rolling quickly on a skateboard, a child is exciting, worth barking at; stop the skateboard, and the motion, and the dog calms.

To live without the abstract is to be consumed by the local: facing each event and object as singular. It is roughly what it means to live in the moment—to live life unburdened by reflection. If it is so, then it would be fair to say that dogs are not reflective. Though they experience the world, they are not also considering their own experiences. While thinking, they are not consulting their own thoughts: thinking about thinking.

What feels like a moment to us may be a series of moments to an animal with a different sensory world. Even our “moments” are briefer than seconds; they are the duration of a noticeable instant, perhaps the smallest distinguishable time unit, as we normally experience the world. Some suggest that this is measurable: it is an eighteenth of a second, the length of time a visual stimulus has to be presented to us before we consciously acknowledge it.

the greetings of all social canids, are similar. In the wild, when parents return to the den, the pups mob them, madly lunging at their mouths in the hope of getting them to regurgitate a bit of the kill they have consumed. They lick at their lips, muzzle, and mouth, take a submissive posture, and wag furiously. As we have seen, what many owners cheerfully describe as “kisses” is face licking, your dog’s attempt to prompt you to regurgitate.

Teach your dog the things you want in a way he can understand: be clear (about what you want him to do), consistent (in what you ask and how you ask it), and tell him when he has got it right (reward him straightaway and often). Good training comes from understanding the mind of a dog—what he perceives and what motivates him.

Few celebrate a dog who jumps at people as they approach—but start with the premise that it is we who keep ourselves (and our faces) unbearably far away, and we can come to a mutual understanding.

Canidness matters: Your dog is a social creature. Do not leave him alone for most of his life.

In the gallop that fifth toelike digit partway up the front leg of most dogs—the dew claw—is used for stability and leverage;

Given the salience of eye contact to all canids, and the dog’s use of gaze, you can get a lot of information about an unknown dog from his eyes. Constant eye contact can be threatening: do not approach a dog by gazing non-stop, which may be perceived as staring him down. If he is staring at you, you can deflect his gaze by turning away slightly, breaking eye contact. They do the same when they are tense: turning their head to the side, or distracting themselves with a yawn or a sudden interest in a smell on the ground. If you think you are the recipient of a threatening stare, you can confirm it by looking for its accompaniment: hackles up, ears up, tail up, body frozen. A stare with a tongue darting licks into the air is more adoring than aggressive.