Horses and colour vision...

metalmare

metalmare

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I read a science based horse book once which discussed the horse's possible scale of colour vision. I seem to think orangey yellows featured.

My welsh cob ignores the yard owner's black and grey trugs but goes mad when he sees his orange feed trug. And of course it's well known that some horses dislike yellow objects such as daffodils.

What are other people's experiences around this?
 
LOL, I should add my cob goes mad in anticipation (in a positive way) when he sees his orange trug.

I once loaned a mare who also was afraid of yellow grit bins :-)
 
Yes horses are partly colour blind

They see the yellow part of the visible light spectrum very clearly. Blue is OK.

Green and red just look like different shades of brown/grey.

I suppose they evolved to not eat the yellow flowers or the yellow and black insects...
 
Maybe. You would think green would be useful for picking out vegetation, but then horses stem from the middle East where vegetation wouldn't have been so green - maybe this is also a factor?
 
They can distinguish most colours from grey apart from bluish-green. What that means is, when presented with two cards (one coloured, the other grey of the same lightness), they can correctly pick the coloured one. They can also tell red from blue. In this way, horses are a bit like red-green colourblind people.

That's normal horses - or rather, the horses that have been tested rigorously. For all we know, there may be horses that have defective colour vision even for horses.
 
I think my horse needs spectacles... if so many people are short sighted surely some horses could be? He's so irrational and depends so much on his hearing... but then he is welsh :-)
 
metalmare said:
I read a science based horse book once which discussed the horse's possible scale of colour vision. I seem to think orangey yellows featured.

My welsh cob ignores the yard owner's black and grey trugs but goes mad when he sees his orange feed trug. And of course it's well known that some horses dislike yellow objects such as daffodils.

What are other people's experiences around this?
Click to expand...


Interesting - my old girl showed a dislike of yellow jump fillers and had to be encouraged to go over them. Ironically her matchy matchy colour was yes, you guessed it - yellow!
 
I've always believed its the blue/indigo/violet part of the spectrum they can't differentiate between, & subtle shades of colour. So bright yellow & pale yellow would appear different, but not say burgundy & dark pink.
My mare used to be very cautious of blue jumps back when she was still hesitant of different fillers, new fences etc.
 
Out of interest is that what a different type of feed comes in? one of mine will choose flat red every time, her field mate high purple. My other flat black. The first two switch when done to lick out each other's bowls but always go to theirs first.
They all know which is theirs.

The only colour I've known any with a problem with was blue. Flowers and tarps on hacks a couple have been a pain.
And black diagonal stripes on jumping poles, not straight stripes though.

Littlun also has an issue with me in any check jackets regardless of colour (have blue, green and red) she tolerates them now but really doesnt relax with them at all.
 
Horses are not colour blind :)
They have dichromatic vision, (as opposed to human trichromatic vision)
Basically means they have rods in the retina for detection of black-white shades, and only 2 types of cone. They see hues of blue and green but dont see red very strongly. Its because they have evolved to be active in dusky light, where they use their rods more :)
 
A friend of mine and member of the Equine Behaviour Forum performed a very elegant study of her cob gelding's colour vision. She is also an artist with lifelong experience of working with colour.

She summarized the results for her horse as a chart with the 28 colours used along the bottom and test score (from 0=invisible to 21=most saturated as estimated by the ability of the horse to differentiate the colour from grey of the same lightness) shown vertically.

The horse did well for most reds apart from the purplish ones. Colours ranging from orange, through yellow to grass green were distinguished perfectly. As the green become bluish the score suddenly dropped to zero - the horse couldn't tell the difference between these colours and the same shade of grey. As the colour progressed into the blue range the score improved, but blues were not distinguished quite as well as orange-yellow-grass green. Then, as the blues became more purply, the score decreased again. Magenta was particularly poorly discriminated.
 
B_2_B said:
This is quite a good video, explains the differences and shows you the stand out yellow/orange near the beginning :)
http://www.youtube.com/watch?v=Dzfu2Pnt8HU
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Nice video presentation! It does contain some inaccuracies though...

"So the horse sees the world in shades of yellow, blue and grey". Actually we don't know what these colours really look like to a horse. When they are looking at yellow, for example, they may not be getting the same sensation as you do when you look at yellow.

Also, a horse doesn't raise and lower its head to focus. That idea, based on dissections done a long time ago seeming to show a "ramped retina", has since been disproved. However, one reason for raising or lowering the head may be to bring something the horse is looking at into full binocular view, so it can see the thing more clearly and better judge how far away it is.

A while back I wrote a bit about equine vision (and other stuff) for a book. You can read it here:

http://www.gla.ac.uk/external/EBF/uhcc7.html
 
We had a affiliated jumping pony that had won a fair bit who would only back off yellow jumps, and my own horse would only shy and pass widely around red cars.
 
fburton said:
Nice video presentation! It does contain some inaccuracies though...

"So the horse sees the world in shades of yellow, blue and grey". Actually we don't know what these colours really look like to a horse. When they are looking at yellow, for example, they may not be getting the same sensation as you do when you look at yellow.

Also, a horse doesn't raise and lower its head to focus. That idea, based on dissections done a long time ago seeming to show a "ramped retina", has since been disproved. However, one reason for raising or lowering the head may be to bring something the horse is looking at into full binocular view, so it can see the thing more clearly and better judge how far away it is.

A while back I wrote a bit about equine vision (and other stuff) for a book. You can read it here:

http://www.gla.ac.uk/external/EBF/uhcc7.html
Click to expand...

Thanks, that's interesting :) I get what you mean about the first bit, I guess it's the easiest way to try to give a general idea, we're never going to know what they see/hear/think I guess but we can try :D
According to our filly, yellow looks edible and yummy :p :D
 
Zargon_91 said:
Horses are not colour blind :)
They have dichromatic vision, (as opposed to human trichromatic vision)
Basically means they have rods in the retina for detection of black-white shades, and only 2 types of cone. They see hues of blue and green but dont see red very strongly. Its because they have evolved to be active in dusky light, where they use their rods more :)
Click to expand...

That's correct. From what I remember horses only have 2 colour cone receptors whereas we have 3.
They do not have 20/20 vision but out of most animal species a horse probably has the better eyesight.
A horse also has the largest eye's of any mammal.
They see much better in low light than we do but it takes longer for their sight to adjust (hence to fear of walking into darkened spaces).
The reason for their vision to lack more colour is so that small movements stand out far more which is why on windy days for example their sight is overloaded with movement whereas we don't really pick up on individual leaf movement.
Good course builders will always take the horses vision into account.
Correct me if I'm wrong as I trying to think back what I learnt.;)
 
B_2_B said:
Thanks, that's interesting :) I get what you mean about the first bit, I guess it's the easiest way to try to give a general idea, we're never going to know what they see/hear/think I guess but we can try :D
Click to expand...
Glad you found it interesting. :) I think the statement about the horse seeing the world in shades of yellow, blue and grey is helpful inasmuch as it conveys the relatively limited nature of their colour vision.
 
cambrica said:
They do not have 20/20 vision but out of most animal species a horse probably has the better eyesight.
Click to expand...

Here's what Brian Timney and Todd Macuda wrote in a review article about horses' vision and hearing:

"Visual acuity—Until recently, systematic studies of the horses’ visual abilities had not been performed, and the literature contains many contradictory claims. Walls suggested that horses have excellent vision, basing his opinion on old stories that Arabian horses could recognize their master from great distances. In contrast, Hebel argued that horses had the poorest acuity of the 5 mammals he studied (pig, sheep, ox, horse, and dog), based on his finding that ganglion cell density outside the visual streak is extremely low. Similarly, François et al assumed that horses have poor vision, which could be explained by the small proportion of cones in the horses’ retina. None of these investigators took direct measurements of a horse’s visual acuity.

More recently, Timney and Keil obtained a quantitative behavioral estimate of resolution acuity in horses, using standard psychophysical procedures. In a 2-choice discrimination task, horses were trained to approach either of 2 trapdoors set into a large board. The positive stimulus was a pattern of black and white stripes, of which width could be varied; the negative stimulus was a pattern of very fine stripes that appeared as a uniform gray. Horses were rewarded with a food pellet hidden behind the trapdoor with wider stripes. By varying the width of the stripes, it was possible to find a stripe width that the horses could not discriminate from the gray at better than the chance performance level of 50% correct. The best acuity obtained was 23.3 cycles/degree."

The acuity of the human eye is roughly twice this (at best), so a horse can't see detail as well as we can (assuming both have reasonably good eyesight). Furthermore, the acuity of a horse is better than a dog and much better than a rat. However, a horse is extremely good at detecting tiny movements and the zone of high acuity extends in a stripe to cover the horizon rather than being restricted to a central spot as in humans - both of which make good sense for a prey species.

By the way, I think the reason horses can tell who is coming at a great distance may be because they are recognizing the way the person moves more than being able to distinguish e.g. facial features.
 
Your last paragraph fits in with my own experiences & observation fburton. I also think the sound of the footfalls help them recognize people, or other animals they can't actually see. My mare for many years has shouted greetings to me long before she could realistically see me, & on some occasions when its physically impossible for her to see me. Our non horsey farmer says he always knows if I'm close to arriving, my mare whinnies a greeting when I'm halfway up the driveway, despite being round the corner where she'd need a periscope to actually see me. Yet other people who in theory have a similar footfall, she ignores. And its not confined to times she expects me. Likewise we've had daughters pony at various places full of similar age kids (shows, brownies, bday parties, school etc) & she can pick daughter out from a crowd, but given the situations when kids all dressed similarly, I believe its movement & sound she distinguishes, not appearance. And as someone with non too wonderful eyesight, I too distinguish horses at a distance by sound & movement. As kids our ponies were in a huge field & large herd. Despite awful eyesight, once we shouted the horses in the dark, I could identify each better than my better sighted friends as they came across the field as I relied on the way each moved & the individual sounds of their hoofbeats. And I imagine a horse does exactly the same.
 
My old pony completely hated white vans. Any other colour vans/white lorries/white cars were all fine but any type of van wether big or small had grumpy faces pulled and the occasional kick aimed in its direction :o he was fine with the farriers white van though ..
 
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