A Focus on Doggy Vision
Have you ever wondered what the world looks like through our dog’s eyes? Are they truly colourblind? Can they really see in the dark? Well, scientists have studied the eyes and behaviour of dogs and have been able to give us the best view of what a dog’s vision is actually like.
Dogs' eyes contain the same types of cells on their retinas as humans, rods and cones. Cones are the cells that are active at higher light levels and are responsible for colour vision. Rods on the other hand are responsible for vision at lower light levels and to detect motion. Humans usually possess 3 types of cones whereas dogs only possess 2, this limits the number and vibrancy of colours that dogs can see. However, dogs do have the upper hand on the number of rods, simply by having a lot more of them. This gives them superior ability to identify motion and to see in very dim lighting.
So, dogs definitely do not live in a black and white world. They are able to see and differentiate colour, but it is more along the same spectrum as a ‘colour-blind’ human limited to blue and yellow. Therefore, dogs are unable to properly distinguish green or oranges, for example orange and green all look a bit yellowish and red appears more dark brown or black to a dog.
Their perception of colour vibrancy is also different, with dogs being less sensitive to changes in brightness. This means that the colours they can perceive are less vibrant and lack the richness that we as humans can perceive.
So how do assistance dogs for the blind tell the difference between traffic light colours? Well, the answer is that they don’t. Their handler will give them a hand signal when they think it is safe to cross by listening to the surges of traffic. The dogs are trained to not walk into on-coming traffic, and they will only lead them across if it is indeed safe to do so.
There are also some other visual differences between canine and humans. Canine vision is not as acute as a human, meaning dogs are more near-sighted with distance objects being blurrier than they would to us. Dogs can still recognise their owners from afar but not because they can make out their faces, it’s usually because they recognise the way that their owners body moves from a distance.
Our dogs can also see in the much lower lighting and detect motion far better than the human eye will allow. A dog's pupil can dilate to the max which allows them to filter in as much light as possible. They also have the addition of reflective cells under the retina known as the tapetum. This is what gives your dog that shiny glow-in-the-dark eyes look and improves their ability to see in dim lighting. The addition of extra rods is also extremely useful in detecting motion giving them the upper hand in visualising the tiniest of movements from far away.
So, in the bright light of day, a dog’s world might be a bit more blurry and a bit less colourful than ours. However, in low light conditions they are definitely leading from the front!