The belief that dogs can only see in black and white has been banished by science – your faithful friend can see in colors. It is true that they do not see all the colors that the human being can perceive, but their vision has a pair of superpowers that make them much better in certain conditions.
Science has shown that dogs don’t see all colors like humans and other animals, but they do outdo us in some low-visibility situations. To understand this, we will first explain how color perception works thanks to the cells we have in our eyes.
How do we see colors?
Humans can distinguish about 10 million colors within the visible spectrum, says the American Academy of Ophthalmology — AAO. The visible spectrum is the electromagnetic radiation that the human eye can perceive. We can see all radiation with a wavelength between 380 to 750 nanometers, that is, the range between ultraviolet light and infrared light.
The ability to perceive colors is due to photoreceptor cells in the retina of the eye called cones, which get activated when there is more light. There are three types of cones, which are differentiated by the type of photoreceptor pigment in each of them (red, green and blue). The human eye has around six million cones.
The brain distinguishes the color of an object that we see according to the number of photoreceptors activated by light that enters the eye after bouncing off the surface of that object.
How do dogs see colors?
Dogs on the other hand only have two types of cones, a study from the University of Cambridge showed. The scientists determined that dogs can see the colors blue and yellow, as well as all their possible combinations since they perceive the visible spectrum comprised between 429 to 555 nanometers.
Another one of the photoreceptor cells that humans and dogs share is the rods. These cells are especially useful for low light environments. Although we have more rods than cones —110 million vs. six million – that doesn’t make us especially better in low-light vision. But dogs do see better than us in the twilight, as they have more rods than cones in the central area of the retina, unlike humans.
As if this were not enough, dogs have one more visual advantage: the tapetum lucidum. It is a layer of tissue containing guanine, a reflective membrane that improves low light vision. Thanks to this membrane, the eyes of cats and dogs shine at night. It is especially an advantage for animals with nocturnal habits, such as cats, which usually hunt at night.