Tuesday, July 17, 2012

Riding In The Dark

Spider by arenalight.

Since it's summer now, and hot, I've been riding at night.  I'm actually getting to like it quite a bit.  There's something oddly relaxing about it.

Humans are very visual creatures.  We rely on our eyes for most of our sensory input. In fact, humans are so dependent on our vision that our other sensory organs have actually atrophied.

I know I spend a lot of my time in the saddle looking at things.....  Looking at my horse's head, looking at my hands, looking at the chicken running across the lawn, looking at the neighbor pulling into his driveway, looking at the arena.  Looking, looking, looking, when what I should be doing is feeling.

But at night, I lose my ability to look.  I have arena lights, but they aren't super bright.  I can tack up by them, and I can make out the boundaries of the arena, but not much else.  I've found that when I'm not so busy looking at things, I tend to concentrate much more on riding.  Without visual distractions, I allow myself to melt into the physical experience of riding.  It's really a lot of fun.

Spider takes to it well, also.  His visual system is organized in an entirely different way from mine.  His eye has a higher concentration light receptors than mine, as well as a secondary structure to amplify the light that enters the eye (the tapetum lucidum, humans do not have a tapetum lucidum).  So, while I am functionally blinded, he can see just fine.

But, lets talk about the differences in our visual systems for a moment....

My human eye has less light receptors and no specialized light amplifier, but it has more color receptors, more muscles,  and more overlap between my visual field (better depth perception).

Spider's horse eye has a much higher number of light receptors:  he can see quite well in low light.  He also has a tapetum lucidum to amplify the light that goes into his eye, enabling him to see in almost complete darkness.  Conversely, this adaptation makes it difficult for him to see in bright light.  Just imagine what it would be like to wear night vision goggles during the day, or remember what it's like when you suddenly take your sunglasses off on a sunny summer afternoon after wearing them all day.

His eye lacks a receptor to see the color red, making him essentially red-green color blind.  This is an adaptation common in animals that are active in low light, the long wavelength of the color red makes it the first color to disappear in low light.  Functionally, it means he sees less contrast than we do.  So, while I can clearly see the orange cone in the arena, Spider can not.  To him, the arena and the cone are pretty much the same color, and he is probably wondering why the footing is erupting into a mini-volcano.

Spider's eyes do not have as many muscles as my human eye.  Humans take it for granted that we can easily focus on objects without moving our head.  I just did it, right now, to look from my keyboard to my computer screen.  By only moving my eyes, I was able to go from focusing on something 6 inches from my face, to focusing on something 2 ft from my face.  And I can easily focus on the wall beyond my computer screen, at least 20 ft away, without moving my head.  I can do this because of the muscles in my eye.  Those muscles can change shape of my eyeball, which changes my ability to focus on things near or far.  Spider's eye is more like a magnifying glass:  When using a magnifying glass, you have to move the actual glass around relative to what you're trying to view.  This is why a horse moves his head around when he's looking at something, he's trying to bring the object in focus.  Just for fun, next time your horse spooks at something, note where his head goes relative to the "scary thing".  If it's close by, his head will go down.  If it's far away, his head will go up.  Which brings us to depth perception....

As a prey animal, Spider has a much wider field of vision than mine.  He can see nearly 350 degrees around himself.  But, of that 350 degrees, only about 65 degrees is binocular vision.  His eyes are placed on the sides of his head, but his head is narrow.  Binocular (two eyed) vision is what gives us the ability to judge depth.  That means that he can only judge distance for things that are directly in front of his head. There is an overlap in his visual field in front of his face (the overlap in each eye's visual field is what gives us depth perception.  Try closing one eye and navigating a room if you want to test that).  So, a horse will always try to maneuver his head relative to an object that has caught his interest, both to improve his depth perception and to improve his ability to focus on the object.

Hmmm, that got all nerdy, didn't it?  Sorry!  The message I was trying to convey is this:

Try riding at night!  It's fun, because you have to give up your visual dominance.

Also, when your horse is acting stupid during the day, try to remember that he isn't seeing things the way you are.  Yes, you can see that it's just a plastic bag sitting by the side of the arena without moving your head.  Yes, you can see that it's just a shadow at the door of the indoor arena.  But, your horse can't see that.  Cut him a little slack.  I promise, it won't make him spoiled and it will make your relationship better.


  1. This is the coolest post. I didn't know those things.

    Science win!

    1. Aww, thanks!

      It does help to understand our horse's physiology. Differing physiologies is not an excuse for poor behavior, but we do need to understand the physiology and apply our training with regard to it.

  2. Hooray for science! You make a good point. Humans are very visual creatures and this does interfere with our other senses and observations. I once had to finish a trail ride in the dark. I was very grateful that my horse could see where we were going, because it was all I could do to avoid a branch in the face.

    We dissect the sheep eye in my class. The tapetum lucidum is a beautiful, iridescent structure at the back of the eye. It is blue-green like peacock feathers. This is why horses and other animals that see well in low light get that "alien eye" look in dark photographs.

    (whispering: red is the longest wavelength of visible light, sorry, I can't help myself)

    1. *Facepalm!* You're so right! Can't believe I made that mistake, I'm going to fix it now. My only excuse is that I sucked at physics, but did remember that there was something about red light that made it less distinguishable in low light situations. Being an ego-centric human, I went with "short wavelength". Very silly! That's what I get for going on memory! And, thanks for pointing that out!!

  3. Great post, and well worth remembering when our horses react to things. As well, sometimes when their heads go up, it's to get a better look at something and when they are "on the bit" their vision is really restricted.

    Enough of that stuff. I like to ride at night too. I have arena lights that a perhaps better than yours, but I am often quite content to simply ride without them. Moonlit nights are wonderful and it rarely gets pitch dark unless it's cloudy.

    When I boarded out my barn had no lights in the outdoor arena, and I'd often prefer that to inside. There is a certain quiet solitude to riding at night. I should be doing more of it.

    1. "There is a certain quiet solitude to riding at night", exactly! You said it perfectly!

      I love riding when the moon is full, too. It's quite magical.

  4. You're so smart :) I imagine riding at night would be pretty cool and certainly a chance for a lesson in trust! Trusting our other senses, trusting the horse, etc. Interesting stuff. I should come out there and take a lesson sometime!

    1. Anytime! You can ride the pony ;)

  5. I couldn't agree more. When I ride at night I feel my balance has to get a lot better. I found this quite un-nerving the first time I noticed it but I have also noticed that my riding has improved becuase I have had to use my other senses to help balance myself. Moonlight is georgeous to ride by, when I have a full momon I love riding out in the big paddock and cantering around on a loose rein and getting lost in the whole moment!


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