Have you ever wondered what life would be like through the eyes of your dog? Would taking a walk in the dark be like night vision goggles? Or would what you see be less important than those mind boggling smells around?
It’s all in the eyes (of the dog)
At the back of our eye, on the retina, we all have rods and cones, which are detectors of light and colour respectively. The more cones we have the more colour we perceive and the more rods we have the more light gets absorbed in our eyes. Humans have more cones than dogs, giving us a beautiful colour spectrum.
Dogs on the other hand have more rods than cones, allowing for better vision in any light conditions and of course at night. Dogs only perceive 2 colours and no one knows exactly which ones! Yellow seems to be a favourite guess! So a dog may see the world a bit more monochromatic than we first thought, perhaps a bit duller overall. New studies liken a dog’s colour spectrum to that of a red-green colourblind person. For example a guide dog can’t distinguish the difference of a green to a red light when crossing the road, but the dog can perceive the change in position of the light hence knowing when it’s safe to cross.
But what dogs do have which we don’t is a special layer within the eye called the tapetum lucid. It reflects more light into the retina allowing for even better night vision! This is what makes a dog’s eyes have that evil eye green tint when photographed with a flash!
Your dog uses motion visibility!
Having more rods than cones also means that dogs have a much better motion visibility than us humans. Their peripheral vision is also wider than ours. This means they can easily see what’s to their far left or right without moving their heads. This affects their focal vision, or straight ahead focus. Dogs need to be closer to a person or object than you do to be able to see it clearly. So when you’re out and about with your dog, he or she is actually reading your body movement signs rather than your shape or facial expression.
I have often noticed this with Chilli in a busy park. When there are many people all walking together wearing pretty much the same clothes (a parka) he needs me to wave or move a little in order to identify me when he is running ahead. Of course smell plays a big role too. Through a whiff of our scent our best friend can identify us.
Motion visibility is a great fact to consider when training your dog. If you wish to introduce silent cues, a slight body movement will speak volumes to your dog. So you won’t need to say the command anymore but just show a slight movement and your dog will know what you want him or her to do.