Horse Husband FAQs: ‘Is your horse colorblind?’

Lorraine Jackson’s “equine curious” husband has been asking her a lot of questions lately–and she’s on a quest to get him the answers. Here’s his latest random query.

Top: Stock photo

From Lorraine:

I found myself in a bit of a lurch last week trying to explain to the Mr. why my 3 year old mare was approximately 13,479 times more frightened of a blue tarp than a gray tarp. I knew horses saw color differently than us, but beyond that, the specifics I may have once known have since been replaced in my brain by college finals cramming, the DC Metro map, and how to use Excel.

Most humans are what we call trichromats. Which means, basically, that our eyes are able to perceive the three primary light spectrum colors and variations of them: red, blue and green (the light spectrum colors being different than the ones you may have learned in art class: red, blue, and yellow. Annoying, I know.)

Our horse friends are dichromats, meaning they perceive only two light spectrums, as are most placental mammals and many insects. Different animal orders will vary slightly in what colors they can perceive, so your horse and dog will have slightly different vision from each other as well.

Studies suggest that the world your horse sees might have a slightly apocalyptic, mustard gas feel to it. Remember this and show tender mercy the next time your horse self-destructs over a grocery bag.

In a 2007 study that was published in the Journal of Comparative Psychology, researchers used dotted vision plates (similar to the ones you see for a human colorblind test) to determine what colors a horse could see. Using treat incentives to teach the horse to choose a certain shape hidden among the dots, they were able to determine when a horse could and could not see a circle on the card. As an interesting side note to equine study, according to Dr. Evelyn Hanggi at the Equine Research Foundation it can take a horse as many as 100 tries before it learns the process of choosing the correct two-dimensional shape in a study such as this, but they CAN learn it!

Hanggi Ingersoll and Waggoner Plates in Horse Vision Study

What they discovered was that the four test horses could definitely perceive blue, and definitely perceive yellow and certain shades of green. They could not distinguish a red circle on a yellow/green background, nor could they perceive a red circle on a gray background. So in essence, a horse’s vision would look something like these examples:




When you go back to that moment in the arena with my mare, my husband, and I, it was much easier to understand her reaction to the blue tarp. Thanks to this study, I not only know why the blue tarp looked so bright and shiny in the eye of my mare, but I also accept that it may take 100 or so tries for her to learn that stepping on one could lead to a reward.

Even more importantly, your horse knows a blue ribbon when it sees one. So get to it, Horse Nation.

Citations and Further Reading:

The full study on equine vision by Evelyn Hanggi, Jerry Ingersoll, and Terrace Waggoner as seen in the Journal of Comparative Psychology in 2007

Equine Behavior: A guide for Veterinarians and Equine Scientists

Traditional Color Deficiency Tests in Humans

Photopigment Basis for Dichromatic Color Vision in the Horse

Lorraine Jackson grew up on a ranch in central Utah where she had more chores than friends, but having horses made it all worth it. She learned to ride under the great tutelage of her mother, the United States Pony Club, and her local 4H Horse Program Chapter. When she was 16, she took her BLM adopted mustang Ralphy to the National Wild Horse and Burro All Around Youth Finals. She took time away from horses to get a degree, go to work, and get married, but now enjoys writing about horses as much as riding them. You can follow her bizarre ramblings on horses, places, ideas, and corn dogs at

lorraine jackson and posie


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