There’s a lot of different myths about how a horse’s vision works and what they can and can’t see, some people will argue that they don’t have depth perception while others will insist that they can only see in black and white. While we’re still a long way off of fully understand how a horse’s eye works we’ve come a long way in our awareness of how they see the world.
How does a horse’s vision work?
Like so many other predated mammals a horse’s eyes are positioned laterally which means they’re on the side of their head instead of on the front (like ours our), this helps to give them a better, and wider, field of vision so they’re able to spot any possible danger and react long before it arrives. That doesn’t mean that they can’t see objects that are close to them though.
As is the case with most animal’s eyes, the exception the skate (the only animal that can’t see color), a horse’s eye is made up of rods and cones that help them to see in low light as well as much higher light levels but that is only part of how a horse’s vision works.
- Rods – Responsible for an animal’s perception of light (or scotopic vision), they allow horses to see in low light.
- Cones – Responsible for controlling an animal’s photopic vision. Horses have two different types of cones that control the colors they can see; short-wavelength (blue), middle wavelength (green). There’s also a long-wavelength cone (present in humans) that allows you to see red but horses don’t have long-wavelength cones.
As well as seeing in a range of light conditions horses actually have two forms of vision and can easily switch between the two, but they do also have small blind spots.
This is where both eyes can be used separately at the same time. It allows the horse to have a wide field of view (almost 360°) although it does limit their perception of depth. Due to the position of a horse’s eyes, even with monocular vision, they have two blind spots; one right in front of them and the other directly behind. Monocular vision allows the horse to see any approaching threats, regardless of the direction they’re coming from.
Similar to how our eyes work, binocular vision allows horses to see directly in front of them with both of their eyes, although they do still have a 3ft (0.9 meters) to 4ft (1.2 meters) blind spot right in front of them. Binocular vision gives the horse the ability to judge distances as well as to focus on objects in front of them.
The monocular and binocular visions combine to give the horse an unparalleled field of view but, because of where the eyes are positioned, they do have blind spots. They have two main spots but also a small region where they only have marginal vision. A horse’s vision runs down his nose and slightly above the level of his eyes, with the blind spot being approximately the width of his body. This is why it’s so important to not have too tight a rein and allow your horse the freedom to move his head while riding. If he’s ridden on the bit (with his forehead vertical to the ground) or behind the bit ( with his nose pointing towards his chest) he’ll only be able to see the dirt below his nose.
Can horses see in the dark?
Some horses will hesitate when you ask them to ride into a dark area which is why people will argue that they can’t see in the dark but this isn’t due to the horse’s inability to see in the dark, after all, they eat enough carrots so should have great night vision!
If you’ve ever watched horses in the field at night (or called them in in the dark) you’ll notice how they can move around without tripping over or bumping into anything, regardless of their speed, if they had poor night vision this just wouldn’t be the case and, let’s be honest, they wouldn’t be able to graze in the dark either.
At the back of a horse’s eye is a membrane known as the tapetum lucidum which is a retroreflector meaning it reflects visible light back through the retina, increasing the amount of light in the eye and therefore a horse’s ability to see in the dark, this and the high number of rods (the part of the eye that controls night vision). So the truth is horses actually have very good night vision, but where they do struggle is with quick changes in light. This is why some horses hesitate before entering a dark area, the same is true for sudden increases in light; it only takes a few seconds for their vision to adapt but its those few seconds that, in the wild at least, can literally be the difference between life and death.
Of course, horses can’t see as well in the dark as say an owl can but that doesn’t mean their vision is poor.
Do horses see color?
Anybody who’s seen a horse shy away from a particular color will tell you that horses can most definitely see color but that doesn’t mean they see color in the same way that we do. The color an eye sees depends on the wavelengths of the cones (short, middle, and long) it has and while we have all three cone wavelengths (known as trichromatic, this allows us to see the full spectrum of red, green, and blue), horses only have two (known as dichromatic) allowing them to see only blue and green, although their middle wavelength cones can see a fraction of red. It’s thought that the reason for this is because when horses first evolved they were more active at dawn and dusk when there’s little need to be able to see red.
Horses do have color deficiencies which make some objects harder to see but not completely invisible. This is one of the reasons why many jumps are painted in bright contrasting colors and evidence certainly backs this up as horses are less likely to knock a fence down if it’s painted in contrasting colors.
Can horses see 360 degrees?
Like many predated animals that spend a lot of time grazing, horses have a very wide range of vision but they don’t quite have a full 360 field of view (even owls don’t have that without rotating their heads). Horses have the largest eyes amongst all land mammals which gives them a wider viewing range than most other animals, allowing them to have a 350 degree range with their monocular vision, even without moving their head at all. There are only two places that a horse can’t see without moving, straight in front of them and right behind them, although they do have a small area of marginal sight either side of their rear blind spot.
While a horse’s binocular vision won’t improve their viewing range it does give them the ability to see straight in front of them, albeit with a very small (3ft to 4ft / 0.9 meters to 1.2 meters) invisible spot.
Do horses have good depth perception?
It’s a long-held myth that, because horses have their eyes on the side of their head, they’re not able to judge distances very well which gives them poor depth perception but this isn’t the case. Yes, there is a moment when a horse approaching an obstacle won’t see it so he’s effectively jumping blind but this is only for a very short period of time.
With just one eye a horse can adequately judge depth, in part because their eyes are positioned slightly further forward which gives them a slight overlap of approximately 55° to 65°. With a tiny movement of the head (ie raising, lowering, or tilting) though they can see into their blind spots, improving their depth perception. This is, of course, with monocular vision, when they use their binocular vision their depth perception is excellent.
There are a lot of myths about how horses see but most of these come from our lack of understanding about how their eyes work and how they see the world.
Horses are nearsighted
People argue that horses are nearsighted and can’t see objects that are far away but this simply isn’t true, after all, horses wouldn’t have survived as long as they have if they couldn’t see approaching danger until it was too late to react. Research carried out by Carol Hall, Ph.D. of Nottingham Trent University shows that while around a third of domestic horses are nearsighted most are actually farsighted, although there can be differences between breeds, you can read the study here. It’s also worth noting though that all wild horses are farsighted.
Horses need to see things from both the left and the right side
All mammals have a structure in their brain, called the corpus callosum, that connects both the left and right hemispheres of the brain and allows information to be shared between both sides. This is most evident in the research carried out by Dr. Hanggi and the Equine Research Foundation. They ran a series of tests, on a number of horses, to demonstrate that one eye can see something that both sides of the brain can understand. The research, which can be read here, involved horses (that had one eye blindfolded) being shown images they’d ever seen before, they were then encouraged to touch one of the pictures for food. The blindfold was then moved to the other eye and the test was repeated, with every single horse touching the same image they had with the other eye every time.
Horses will sometimes shy from something familiar but this isn’t because they’ve only seen it with one eye, instead it’s likely to be the light is affecting the contrast and shadows so the object looks slightly different. This is often the same for us too, after all, how often have you been out in the snow and commented on how the blanket of white makes everything look very different.
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- Safely riding in the snow
- How horses show affection
- Can horses swim?
- What your horse’s teeth tell you
- How smart are horses?
- How do horses sleep?
- Reading your horse’s body language
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