NAUTILUS: Some animals, including your pets, may be partially colorblind, and yet certain aspects of their vision are superior to your own. Living creatures’ visual perception of the surrounding world depends on how their eyes process light. Humans are trichromats—meaning that our eyes have three types of the photoreceptors known as cone cells, which are sensitive to the colors red, green, and blue. A different type of photoreceptors, called rods, detect small amounts of light; this allows us to see in the dark. Animals process light differently—some creatures have only two types of photoreceptors, which renders them partially colorblind, some have four, which enables them to see ultraviolet light, and others can detect polarized light, meaning light waves that are oscillating in the same plane.

“None of us can resist thinking that we can imagine what another animal is thinking,” says Thomas Cronin, a professor at the University of Maryland who studies visual physiology. But while guessing animals’ thoughts is a fantasy, looking at the world through their eyes is possible. Read more.