You might be convinced that your horse can see every color in the rainbow because he always spooks at the red and white painted poles or the yellow flowers in front of the judge’s booth.
For many years, it was assumed that horses were colorblind or mostly colorblind, but recent studies have identified that horses do see color, just not the way we do.
The cone cells of the eye are responsible for color vision, and they are situated at the back of the horse’s eye. Humans have three types of cone cells (trichromatic) but horses only have two types (dichromatic). Color vision requires at least two types of cone cells, so we know that horses can see color, albeit a reduced variation of specific colors than we do. There are dichromatic people, too, which we call “colorblind.”
In addition to seeing a reduced variation of color, horses see less detail than humans because evolutionarily, they rely on other highly developed senses to sense predators. Understanding what your horse can see is important in understanding equine behavior, which can pay off in spades in your riding and training.