Q: What colours can horses see?
A: Horses are not colour blind but they can’t see the same colours as we do. Horses have what we call ‘dichromatic vision’, meaning that they differentiate colours in two wavelength regions. Humans have ‘trichromatic vision’, meaning that we see in three-colour wavelengths. Horses can naturally see blue and green colours of the spectrum and their colour perception will vary from object to object. They can’t see red, and will perceive red as a shade of green.
Horses have superior night vision and their vision also improves in cloudy and overcast conditions – tools that help them to survive as prey animals. They can make out shapes and detect movement in very low-light environments. What they aren’t able to do as well as us is adjust to sudden changes of light, such as walking into a dark barn or stable after being in bright light outside. This is the sort of thing that needs to be considered when dealing with problems such as a horse not wanting to load into a box.
It is also worth noting that most horses are near-sighted, which is why they can show nervous or spooky behaviour when they detect movement in the distance.