Thursday 16 February 2012

Olympic Countdown - Equestrianism

Researchers at Nottingham Trent University have been studying the eye movements of horse riders. A show-jumper, an event rider, a cross-country rider and a non-competitive rider completed five rounds of a three-jump course wearing a spectacle-mounted device that tells the researchers where the rider is looking, and how long for. As they approached a jump, all the riders changed their point of fixation from the ground to the jump, and then to the ground beyond. The difference, however, was that the more experienced show-jumper focused on the top rail of the jump much sooner than each of the other riders – up to 3.05 seconds before take-off – and holds it there until take-off. It shouldn’t really be a surprise that in order to time your jump accurately, you need to focus on the obstacle, and not on the ground in front of it. In fact, Laurent, Dinh Phung & Ripoll (1989) have already shown that riders use the increasing size of the image of the obstacle that is formed on their retina to adjust the horse’s gait as it approaches the jump. It would be really interesting to know if the horse does this as well. The eyes of horses are much more widely spread than in humans, so they have a wider peripheral vision, but don’t tend to focus on specific objects as closely as we do. They are also less likely to have as good depth perception, so may not be as accurate at judging distances. They can learn when to jump, however, as long as they are allowed to keep their head up so they can focus on the top of the jump, like the rider. There has been a tendency to design jumps that test the rider, without taking into account the vision of the horse, but our knowledge is gradually improving. Stachurska et al (2002), for instance, found that horses exhibited refusals and “run-outs” when approaching walls, and that the second elements of combination fences prove more problematic than the first or third obstacle of combination fences. They also found that fences with a single colour (especially white) caused more problems than fences with contrasting colours. They also have problems when green is paired with yellow or blue in the colour of a fence. It’s very difficult, if not impossible, to attach eye-tracking cameras to a horse, partly because of the position of their eyes. But I suspect that horses can learn to focus on the top of an obstacle in order to time the jump, and can probably pick it up rather quicker than many riders. David Donner

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