Full Program Transcript:
Narration: In the thousands of years we’ve been riding horses, you’d think we’d know everything about how horses see. But science has news for riders. They may be surprised to discover they’ve actually been riding blind.

In science, just as in horse sports, it’s easy to be blinded by tradition. Just because something has been in the textbooks for a hundred years, it must be true. So to see what’s really there, sometimes it takes someone to come along and look at it through fresh eyes. In this case, the eyes to look through were the eyes of a horse. When Dr Alison Harman took a fresh look at how horses see, she never expected to overturn all accepted wisdom. She’s a horse-rider and a neuroscientist. And her quest began with a strange accident.

Alison Harman: Years ago I saw a couple of people who were practicing a dressage test with two people at once, a pas de deux, and they both started cantering around the arena and as they came to the bottom of the arena, they actually crashed headlong into one another. And at the time I thought, that’s very strange, why didn’t the horse stop or something.

Narration: While intrigued, she didn’t take it further. But then Alison got interested in an equally strange aspect of horse vision, described in textbooks. This is Dukes Physiology, 1993 Edition. It says that the horse has an eye unlike any other animal. It’s called a ramp retina and it works a bit like bifocals. The horse puts its head down to see long distances, and up to see short distances. And that’s what most of the textbooks have been saying for the last hundred years.

Alison Harman: Well, I heard that the horse had a ramp retina and I always assumed that that was true and I didn’t think about it very much and then one day I started noticing that other animals didn’t have one and I wondered why a horse did. This time Alison was determined to investigate. She got some horse eyes, looked at the back of the eye, and found – well – nothing unusual about the shape of the retina.

Alison Harman: Well, it just turned out that the ramp retina was just a load of rubbish.

Narration: If it was so wrong, how did it go unnoticed for so long?

Alison Harman: Well, I guess no one thought to look. Well, this is not uncommon in science in fact. There are a lot of times when people do just quote other people without really thinking about whether they should check the original reference and sometimes they really ought to.

Narration: So if the long held theory of the ramp retina was wrong, what else didn’t we know about horse vision? Curious, Alison decided next to dissect the transparent retina from the back of the eye, and look at the cells the horse uses to see.

Alison Harman: Well, what we found was that the horse has got something completely different to what we’ve got. It’s actually got something called a visual streak.

Narration: As this computer image of the retina shows, the visual streak is a cluster of cells in a long strip. By contrast, the human eye has a cluster of cells in a tiny point. It means we see the world very differently.

Narration: It’s very hard for us to understand actually – because even if you put it on a piece of paper and show someone, they think they’re just seeing a wide picture. They’re not seeing a wide picture, they’re seeing all the way from there all the way back to there and all the way back to there on both sides. So it’s something that we really can’t conceive of. To us, this view of Kings Park is to the front only. But a horse sees a clear, narrow strip running right around 320 degrees. Above and below that strip is blurred. What’s more, it can’t see the colour red.

There was just one more major test to do. This was a test of the limits of the horse’s vision. Just how far could it see forward, up, down and sideways. And that’s when Alison got her biggest surprise.

Alison Harman: OK, make sure he’s got his head straight. OK I can see eye shine round to there.

Narration: An ophthalmoscope was used to look at the shiny retina, and determine the horse’s field of view.

Alison Harman: When I go across here, it’s gone. It’s not going across here at all.

Narration: To Alison’s astonishment, the field of view ran in the direction of the nose.

Alison Harman: Instead of it being in front of their head the way it is for us, it’s actually down their nose and sort of towards the ground.

Narration: Above and below the nose, the horse simply couldn’t see. Suddenly, Alison grasped the disturbing implications for how we ride horses. Because when the horse’s head is loose, it can put it’s nose up to look forward. But when a horse is ridden in the classical position, its nose points down.

Alison Harman: It was a bit of a shock to discover that in fact they can’t see when their heads are pulled in like that. And it’s really rather a scary thought that people are riding around so much these days with their horses like that.

Narration: To demonstrate what she means, Alison takes me to the arena. Well, this horse has been traditionally trained and I’m going to ride her around with her head in a whole lot of different positions, and we’ll just see what happens.

Alison Harman: Okay now Jonica is riding the horse quite over-bent with the horse’s head behind the vertical. What it actually sees when its head is right down low and behind the vertical is it’s really seeing the ground in front of its feet. It can’t see what’s directly in front of it. Jonica, can you try and ride the horse now on front of vertical. Yes, that’s almost better there. That’s more or less right.

Jonica Newby: But there is a disadvantage to riding like this. This horse doesn’t know me or trust me. I realise now she can see, she wants to think for herself.

Alison Harman: Now it doesn’t feel as safe to Jonica I’m sure because she feels that the horse is going to start spooking, because it can actually now see where it’s going.

Narration: Which is exactly what happens next. A sudden movement. The head goes right up. And we’re spooked.

Jonica Newby: She’s a bit of fun today.

Alison Harman: Yeah, that was a great spook that one.

Narration: Alison now believes this so called “spooking” behaviour is the reason the nose down position became popular in the first place. To the rider, the horse feels more obedient like that. What no one ever realised is that it’s obedient because it can’t see where its going. At last Alison understands why those earlier horses crashed.

Alison Harman: I now realise the reason they didn’t do anything was because they couldn’t see, they were assuming their riders were guiding them safely, and the riders weren’t looking where they were going either.

Narration: While Alison doesn’t expect the grand traditions of riding to change, she does want riders to understand their responsibility. As for Alison herself, she’ll never again ride her horse blind.

Alison Harman: I would rather have a horse which is calm and obedient and submissive but able to see at the same time, because I know it really is being calm and obedient then. It’s not being submissive because it has to be. Because it can’t see.