What do dogs see?


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Dog Vision: What do dogs see?

Most of people have their own dogs as the pets. And many dog owners know the facts: dogs have a much great ability to see in the dark. But few of them know what do dogs see? In fact, dogs see the world very differently to humans. Their eyesight has evolved to allow them to see better than us in certain conditions and less than in others.

So what dogs can & can’t see?

I hope the followings can help you to know more about your dog vision.

Dogs can see four times better than humans in the dark
Because of its history as a predator, the dog’s visual system is designed to operate at its best in low lighting. As with humans their retinas are made up of a mixture of rod and cone photoreceptors, but with the emphasis more on rods, which work much better in dim light. Cones control colour vision and require bright light. As a result of this, dogs need only about one quarter of the light that humans do to see things at night.

Dog can see the range of colours made up of yellows and blues
Dogs can not see the range of colours that humans do. But dogs aren’t colorur blind. A study of dogs concluded that they see a range of colours predominantly made up of yellows and blues. So rather than a rainbow of red, orange, yellow, green, blue, indigo and violet, dogs see an arc of very dark grey, dark yellow or brown, light yellow, gray, light blue and dark blue. When presented with different shades of grey, dogs are only about half as good as humans at telling the difference between them.

Dogs can see flickering lights at a high frequency
Unlike humans, for whom flashing lights blend into one at a frequency of between 50 and 60 Hz, dogs can keep seeing flickering up to a frequency of 70 Hz. This is why dogs don’t always show much interests in television, which – at least, in its pre-digital form – consisted of a series of fast-moving lines. What appeared to us as a steady stream of images appears to them as little more than a rapidly flickering collection of shapes and lights.

Dogs can’t see far away
Dogs have, on average, 20-75 vision, that is they can only see from a distance of 20 feet fine details that a person with good eyesight can see from 75 feet away. They would not pass a driving test with such poor eyesight.

Dogs can’t see the details behind their heads
Dogs have a large blind spot behind their heads.The size of this depends on the size of the dog’s head and so varies enormously from breed to breed. While the blind spot in a narrow-headed Borzoi is only 70 degrees, in the wider-headed Pekingese it is140 degrees, leaving them much more vulnerable to attacks from behind.

Dogs can’t see “Depth of field”
Dogs also don’t have great “depth of field” to their vision. Because they have such large pupils, when they look at things that are distant they only see the objects in the centre of the image in focus. Everything else in the image appears fuzzy. They may not be able to see behind them or in fine detail, but dogs can see things at great distances – especially if they are moving. A test of 14 police dogs found that dogs could recognise a moving object almost half a mile away. If it is stationary just over 600 yards.

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