2001 S. Lincoln Ave. By Sarah Probst Information Specialist University of Illinois College of Veterinary Medicine Owners who want to better understand their canine companions must recognize that dogs see the world from a different visual perspective. The differences begin with the structure of the eye. Cones provide color perception and detailed sight, while rods detect motion and vision in dim light. However, because they have only about one-tenth the concentration of cones that humans have, dogs do not see colors as humans do.
Dogs are unable to distinguish among green, yellow, orange, and red.
They also have difficulty differentiating greens and grays. This and the flow and noise of traffic will tell the dog that it is the right time to cross the street. The set of dog's eyes determines the amount of field of view and depth perception. Prey species tend to have eyes set on the sides of their head because the increased field of view allows them to see approaching predators. Predator species, like humans and dogs, have eyes set closer together.