I recently read a well-presented Q&A on the blog of Tzena Mayersak about whether horses see color. I could tell she wanted to give her student the best answer possible, so she took the time to read, think and write a great reply to the question "Do horses see in color?" I asked her if she would allow me to post her article on my site for this week's Ask Cherry and she consented. Thank you Tzena and best of luck to you !

From http://tzenateachestrotting.blogspot.com/

I had a student ask me a couple of weeks ago if horses see in color. I thought about it and said, “Well, as I understand it I don’t think they see all the colors we do, I think they see in shades of color…kinda like cats.” It was a reasonably lucky assumption on my part, but I wanted to know the specifics of if horses can see in color and what colors they do see.

It is a given that horses have a different field of vision than we do simply cause their eyes are built and located differently than ours. Because horses eyes are on the sides of their head (as opposed to the front like cats or like ours) the horse views a much larger field of vision.

In their book The Body Language of Horses, published in 1980, Tom Ainslie and Bonnie Ledbetter state, “Many authorities have proposed that horses are nearsighted as well as color blind. Experimental findings support both contentions, but not persuasively.” (1)

As time progress our understanding and research progressed. As discussed in Desmond Morris’s book Horsewatching: Why does a horse whinny and everything else you ever wanted to know, published in 1988, he sates that “For many years horses were said to be color blind but we now know that this is not the case, although color vision is much weaker in them than it is in us. They are most responsive to yellows, then greens, then blues, and least of all reds, according to recent experiments.” (2)

William Micklem, in his book Complete Horse Riding Manual – published in 2003 – he says that “Research has shown that horses are dichromates, which means that they have limited color vision. They can distinguish between light and dark, between reds and blues, but not between greens and grays. This is why you will not find green or gray poles used in a grass showjumping arena.” (3)

Cherry Hill, in her book How to Think Like a Horse: The Essential Handbook for Understand Why Horses Do What They Do – published in 2006, she supports Micklem’s assertion that horses are dichromates. “The horse’s eye has two types of cone cells in the retina that are sensitive to color whereas a human has three types of cone cells. Whether horses can see colors as we do is still widely debated. Most researches agree that horses do have more than “shades of gray” discrimination but not the color range of humans. Exactly which colors horses see is sill unresolved.” (4)

“Equine vision expert Dr. Brian Timney, of the University of Western Ontario, explains that horses are like humans with color deficiencies. For example, humans with red-green color vision defects have only two hues (blue and yellow) rather than four. Such dichromates do not see intermediate hues, seeing instead white or gray or a faded form of the two colors.” (5)

“Horses have little difficulty in discriminating red or blue from gray. With respect to green and yellow, the results are mixed,” says Timney. His findings are similar to those from earlier studies but other researchers’ results differ. Exact answers have proven elusive in color vision research because of the difficulty in designing experiments with adequate controls (such as for brightness).” (5)

In the end, there is still debate about what colors horses see. It would be fair to say that there is a general agreement that horses can see colors, yet what colors those are remains to be conclusively confirmed.

End Notes:
(1) Ainslie, Tom & Bonnie Ledbetter. The Body Language of Horses: Revealing the Nature of Equine Needs, Wishes and Emotions and How Horses Communicate Them - For Owners, Breeders, Trainers, ... Other Horse Lovers Including Handicappers. William Morrow and Company, New York. 1980. Page 30.
(2) Morris, Desmond. Horsewatching: Why does a horse whinny and everything else you ever wanted to know. Crown Publishers, Inc., New York. 1988. Page 41.
(3) Micklem, William. Complete Horse Riding Manual. Dorling Kindersley Limited, New York. 2003. Page 46.
(4) Hill, Cherry. How to Think Like a Horse: The Essential Handbook for Understanding Why Horses Do What They Do. Storey Publishing, North Adams, MA. 2006. Page 24.
(5) Hanggi, M.S., Ph.D, Evelyn B. “How Horses See.” http://www.completerider.com/horsemanfeb2003.html. Feb 2003."

Tzena Mayersak