What do dogs (or wolves, for that matter) see?

Dogs don’t see the world in black-and-white. Rather, their vision is most similar to people with red-green color blindness. But there are other ways dogs differ from humans.

First, let’s consider eye position. Like a lot of carnivores, the eyes of most canines don’t point straight ahead, but are directed slightly outward. Compared to humans, their eyes are spaced more widely. Cognitive scientist Alexandra Horowitz has noted that this enhances peripheral vision and “a panoramic view of the environment: 250 to 270 degrees, as contrasted to humans’ 180 degrees.” This comes at the expense of depth perception, however, because there is less overlap in the visual field as compared to humans.

The visual system of dogs evolved to function well in low light. Dark places make it hard to discriminate colors, so the ancestors of dogs de-emphasized color vision in favor of being able to see in low light and to perceive the motion of objects better than humans.

Humans (and dogs) have two types of color receptors: rods and cones. Rods handle peripheral and night vision — brightness and shades of gray. Cones deal with day vision and color perception. Each of the cones detects a different wavelength of light, and through using our three types of cones, humans can detect a full spectrum of hues (in a similar way to how you mix primary colors in paint). Dogs only have two types of cones (like red-green colorblind humans), and this makes their color vision very limited. Red is difficult for dogs to see. It may appear as a very dark brownish gray or perhaps even a black.

Dogs have the tremendous ability to see ultraviolet light, meaning their world is only roughly the same as ours.  While we would call dogs color blind, they can see farther into the ultraviolet than humans. This means, for example, that dogs can easily spot old urine, which is active in the UV. Furthermore, there is evidence that dogs can see the Earth’s magnetic field. (Dogs align themselves north-south when they pee.)

Dogs are also nearsighted compared to humans. A test custom-made for dogs has estimated their visual acuity at around 20/75 vision (according to Psychology Today). This means a human could barely see at 75 feet is what a dog can just about make out at 20 feet.

The picture above is an attempt to show what a human would see (left side) with what a dog would see (right side). But, before we feel sorry for dogs, we should remember that a dog’s far better sense of smell helps them locate things that humans can’t detect. Given that they are better in low light, as well as at detecting UV light, means that they see very different things than humans.

Why am I thinking about this? Well, if one is writing about werewolves, one does… I assume that for their Night under the full moon, werewolves perceive things as wolves/dogs do. That means faster processing of motion, particularly in low light, a wider field of vision, and the ability to detect out into the UV. Things are kinda blurry for our werewolves, but there must be some sort of smell-o-vision integrated with their perception of light.

And, let’s assume vampires glow a bit in the ultraviolet…just for grins. This would make werewolves excellent at detecting their Undead enemies.