The difference between animal vision and human vision

Four Versus Two. What does it matter?

“The Difference Between Animal Vision and Human Vision

Pg 39 Animals in Translation

What is the difference between how animals and humans actually perceive things around them?

Although I created this list for cattle and hogs, you can use this list to predict trouble spots for any other animal if you think about what these eighteen distracters have in common.

First of all, fourteen out of the eighteen distracters are visual, and I wouldn’t be surprised to find a ration like that for most animals. But to predict what kind of visual object will distract or frighten an animal, you have to know more about what animal vision is like. It’s pretty different from ours. For instance, you always hear that dogs “don’t see well,” which is true as far as it goes. Dogs don’t have very good visual acuity, which is the ability to see the tiny details of what you’re looking at clearly and crisply. People with 20/20 vision have excellent visual acuity, and a lot of animals don’t. That means that most animals aren’t going to be frightened by tiny objects, simply because they can’t see them well.

A typical dog has a visual acuity of 20/75, which means that a dog has to stand twenty feet away to clearly see an object a person with normal vision sees well standing seventy-five feet away. The dog has to get much closer to the object than we do. This isn’t due to nearsightedness but to the fact that dogs have fewer cones in their retinas than people do. Everyone probably remembers from biology class that cones handle color and daytime vision, and rods handle nighttime vision. Basically dogs have traded good visual acuity for good nighttime vision. A dog doesn’t see any object as sharply as a person does, including an object that’s right under his nose. That’s why it’s so hard for dogs to see a piece of kibble you’ve dropped on the floor for them to eat. If they didn’t watch it fall, most dogs can’t see it lying on a mottle colored tile floor (though some can).

There’s also a lot of variation in visual acuity among the different breeds of dogs, as well as among individuals of a breed. One study found that 53 percent of German shepherds and 64 percent of Rottweilers were nearsighted. You might wonder whether being nearsighted matters to a dog since everything it sees is fuzzy to start out with, but test show that it does. A nearsighted dog has much worse visual acuity than a normal-sighted dog. Interestingly, although German shepherds tend to be nearsighted, only 15 percent of the Shepherds in a demanding program for guide dogs were myopic. Probably the nearsighted dogs were flunking out of the program without trainers’ knowing why.

Another huge difference between animals and people is that most animals have panoramic vision. The eyes of prey animals like horses, sheep, and cows are set so far apart that they can literally see behind their heads. THat’s why some hansom cab horses wear blinkers; they can see everything going on behind them, and they get distracted. Most racehorses don’t wear blinkers for the same reason: their trainers want them to know exactly where the horses behind them are, and how fast they’re moving.

Prey animals don’t have perfect 360-degree vision, although they come close. There’s one small blind spot directly behind a cow or horse that you have to be careful not to sneak up to. The animal can’t tell what you are, and he might get scared and last out and kick you. Prey animals also have a small blind spot directly in front of their heads because their eyes are set so far to the sides.

Even though their eyes are so far apart, prey animals do have depth perception, though it seems to be different from ours. We use binocular vision, which means each eye is seeing the same thing from a slightly different angle. When our brains combine the angles, we get our sense of depth.

Prey animals’ eyes are so far apart that a lot of researchers have assumed their left eye was seeing something completely different from the right eye, so they couldn’t have binocular vision. But they’ve tested this in sheep, and sheep do have at least  some binocular vision. We know this because sheep can see the cliff in visual cliff experiments. In the original visual cliff studies the experimenters put a baby on top ofa table covered in a sheet of glass thick enough to crawl on. Directly underneath the glass there was a checkered surface that, midway across the table, suddenly dropped off way below the glass surface. It was a visual cliff, not a real one, so the baby couldn’t actually fall over the edge if he crawled out over the dropoff. Very young babies will refuse to crawl over the cliff, either, which means they have to be seeing the difference in depth. (On the other hand, sheep don’t appear to have depth perception while they’re moving, only when they stand still.)

You’ve probably seen bulls in bullfights lower their heads before they charge the matador. Border collies do the exact same thing when they’re herding sheep. They lower their heads below their shoulders and stare at the sheep. They do this because their retinas are different from ours. The human retina has a fovea, which is a round spot in the back of the eye where you get your best vision. Domestic animals and fast animals who live on the open plains like antelopes and gazelles have a visual streak instead of a fovea. The visual streak is a straight line across the back of the retina. When you see an animal lower its head to look at something, it’s probably getting the image lined up on its visual streak. Most experts think the streak helps animals scan the horizon.

Researchers have also found that of the meat-eating animals that have been tested so far, the two fastest animals–the cheetah and the greyhound–also have the most highly developed visual streaks. Their visual streaks are dense with photoreceptors, giving them extra-acute vision. To test visual acuity you can use a bar code design. The more acute your vision, the tier a bar code design. The more acute your vision, the tinier a bar code you can look at, from a greater distance, and still see the stripes as separate rather than as a gray square. Animals with super-acute vision can also see separate grains of sand on the beach.”

Animals do perceive reality in many ways unintelligible to many people. Animals do what they do often because of instinct which can include either fear or dominance. When dogs perceive a threat or danger, they tend to become more reliant on instinct and much less on operant conditioning. This is a main reason why when a dog sees a rabbit or other animal, it forgets the cookie in your hand. Let’s remember that dogs in nature would be predators and no matter how many pink fluffy beds we buy them, nature is nature. This does not mean that your dog does not love you, and it certainly doesn’t mean that he is ignoring you. What it does mean, however, is that he is being a dog. Dogs do what dogs do because they are dogs. Just as people do what people do because they are people. Men do what men do because they are men. And women do what women do because they are women. Get the picture? It is virtually impossible to remove instinct from an animal just as a dark haired woman can dye her hair blonde but it will continue to grow dark at the roots. The hair grows because the DNA tells it to grow that color. Similarly, a dog with a strong prey drive does not act out of disrespect for you, but rather for respect of nature. As Dr. Grandin so eloquently relays to us, animals can become acclimated to novel and unfamiliar stimuli.

• “The Science of Animal Behaviour”™ (to be a section placed somewhere on WL *Janice and Temple)

Dogs have vision that is different from that of humans. Each breed has a different type and purpose for its sight. Dogs who are herding or sporting breeds tend to have better vision than many and sighthounds such as Rhodesian Ridgebacks, Greyhounds and Irish Wolfhounds tend to have much better vision for longer distances. This is part of breeding for acquired traits. Each breed was bred with a specific purpose in mind and that is why different breeds have been created over hundreds or thousands of years.

Predators often have their eyes spaced out more closely together and are able to focus at longer distances. An animal that might be dinner, such as a bunny, deer or other prey animal has eyes that are farther apart and this is very helpful in their quest not to become dinner. Predators, however, tend to have a specific part of their visual field that has better vision and they will raise or drop their heads in order to see potential threats or dangers. Animals tend to have more reactivity at night, probably because many animals begin to stir under the cover of darkness. Darkness can protect some while stimulating others. This is just one reason that introducing new people and dogs at night is not always a wise choice. We are all more alert and wary in darkness. The higher the contrast of black and white ability, the better an animal’s vision at night will be. This is also most likely responsible for animals being afraid of falling into a dark section of a floor or dark and light alternating tiles. The dark tiles seem to be far below the lighter colored panels. Close one eye and look at a dark tile next to a white tile. You will see how the dark recedes and the light protrudes. The less reactive a dog is to new stimuli, the better he will be with new people, places and things.

*pg 45. “Fear of the Unknown is universal”

“The Science of Death”

Predators think in a way much different from prey animals. Even your cute fluffy maltese in nature will become a predator. How many of us see our own dogs shredding stuffed toys and ripping squeakers out of stuffed squirrels? Well anytime your dog is shaking a toy back and forth or squeaking the squeaker, that represents a prey animal being killed. If your dog has no behavioural issues knock your socks off and buy him every fuzzy chipmunk, goose, hedgehog and squeaky anything because it won’t matter, however, if you have a dog who begins to hunt for things outside, you are engaging his predator instinct. Thus when your dog plays with a stuffed squeaky toy and then sees a chipmunk or tiny dog on a retractable lead, that novel or unfamiliar animal may be perceived by your dog as food or a prey animal. Dogs who have instincts such as herding breeds or sporting breeds, are more likely to exhibit these behaviours and traits since it is bred into them, often for thousands of years. For this reason, encouraging your dog’s prey drive may seem fun and even cute, but when the dog attacks the neighbor’s cat or tiny dog, it may not build good will among neighbors.

Often, a dog on its own will attempt to investigate a new piece of furniture or type of sculpture in a home and since no one is forcing the issue, the dog will probably get through it on its own. There is no artificial constraint of people continuing to tell the dog, “It’s OK.” when the dog is fearful and in fight or flight mode. Refer to section on “Introducing New People or Items to Your Dog” SHHHH HAPPENS.

Repeating the words “It’s OK.” to your dog simply reinforce his fears for dominance by telling him it’s okay to do what he is doing and feel what he is feeling. In these situations, particularly, we don’t want to use words that confuse the dog. The dog does not understand what the words, “It’s okay, Fido. It’s only the mailman. The mailman comes everyday and brings us our mail so you don’t need to attack him through the window every day. It’s okay.” He hears instead, “Blah blah blah. Blah blah blah, blah blah.” Your dog sees the mailman as a potential threat who walks up every day and tries to break into your home and even opens the door sometimes. Your dog does not understand that he is a US Postal Service employee whose job it is to bring you your mail. All your dog understands is that everyday a man in a uniform comes up to your door, attempts to break in and do you bodily harm, and when your dog bark and goes berserk at the door or window, this interloper is scared off because your dog is barking so ferociously. He is barking so furiously that he managed to scare them away, again, six days a week.

People who are shorter tend to appear as less of a threat than tall or larger people. Tall men in hats may appear more menacing or threatening because of their size but try this experiment. Have one person sit in a chair and sit up tall. Have a second person kneel down on the ground and get low without throwing out their back. The person on the floor should look up at the person on the chair. When you do this exercise, switch the two people’s position. The perspective is amazing. Remember, most dogs are far smaller than most people. So you will begin to get an idea of how a dog will get intimidated by certain people or other animals. Remember that in nature, larger presences are seen as being greater threats. A large or tall person bending over and reaching over the head of a dog in order to pet it, would be seen by a dog as a threat much in the same way that a large construction crane hovering overhead might be seen as an extreme danger to someone walking underneath it.

Motion can also spook or shock an animal, particularly the herding breeds, which are bred to be OCD and hypersensitive to movement. Herding dogs can hyperfocus on an animal in their care such as a sheep or cattle, so that when the animal is still and quiet, the dog does not react, however when the animal begins to move, particularly quickly or suddenly the dog suddenly races to stop that movement or guide it to a specific location. This is why many dogs have issues with toddlers or little dogs and animals who move very quickly. It is as much a part of nature as can be imagined. There is movement. I must stop the movement. I must chase it until it stops. This is how your dog thinks.

When we think of perspective, “Think Like A Dog”™. The larger or taller a novel stimulus, the greater the perceived threat. This is one reason that many dogs will be more reactive with a standing person than with a seated person.

When animals are born they rely heavily on sense of smell. The first ten to fourteen days of a puppy’s life, it has only its sense of smell on which to rely. This is when dogs have very little defense against predators and no way to protect themselves. At about ten to fourteen days, the dog’s eyes open and he begins to see. About a week or ten days later, the puppy’s ears open and now he can hear. Thus, dogs always rely first on their sense of smell in approaching new people or things. This is part of the reason that dogs behind a fence, gate or in a crate bark seemingly ferociously when they see a dog or other stimulus but cannot get to it in order to smell. Imagine your little four year old son seeing his best buddy across the street. Your little boy yells out to his friend, “Johnny! Hi! I wanna come say hi!” Mom probably says that they are too busy or can’t go but the little boy continues to try to yell out to his friend. The little boy is not being disrespectful or bratty but rather he is trying to engage his little buddy. Dogs don’t do this. But dogs need to smell first and then see and then hear the stimuli. Dogs are dogs and dogs do what dogs do because they are dogs.

When a dog perceives danger and feels that he is forced into a bad situation, he may block (link to glossary) and refuse to move forward. This is generally out of fear and uncertainty.