For decades, scientists debated exactly what dogs see. The definitive answer came from a landmark study at the University of California, Santa Barbara.
The Study: Color vision in the dog (Neitz et al., Visual Neuroscience)
The Science: Researchers mapped the canine retina and discovered that dogs are dichromats. They possess two types of color-detecting cone receptors (whereas humans have three). Their eyes are optimized to capture two primary wavelengths: short-wave blue (429 nm) and long-wave yellow (555 nm).
What this means for your dog: That bright red or orange ball you throw into the green grass? To your dog, it blends into a muddy, confusing shade of gray or brown. But a blue or yellow toy? It practically glows against the grass, making it instantly recognizable.

