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The convention of leading and mounting the horse from the left might be more than just tradition, according to a new study from St. Andrews University. The study, led by Kate Farmer, MA, at the Harmony Center in Austria, shows that horses generally prefer this arrangement too, and not just because this is how they are trained.
The researchers compared two groups of horses: one trained predominantly from the left and another trained equally on either side. They put them in various situations in which they interacted with people. The researchers found that most horses, regardless of how they were handled, favored their left eye and wanted to keep people in their left line of vision.
Farmer said a good example of this is when a horse refuses to longe to the right. This is often put this down to stubbornness, but Farmer said it is more likely the horse just wants to keep the person in its left line of vision.
"When this happens, the handler needs to give the horse the confidence to have the person on the right, not to punish it or force it," she said. A horse that refuses to work with a person on the right might see him or her as a threat, and the trainer needs to be sensitive and patient to correct that perception.
"It has been shown that the left eye is the 'rapid-reaction' eye, and has a stronger and faster flight reaction to a frightening stimulus presented on the left." Farmer explained. "Our study suggests this affects the horse's interaction with people, too.
"The horse that generally prefers you on the left, but isn't bothered if you are on the right, is probably seeing you as a cooperative partner, whose lead it would like to follow. Trainers should work to achieve a situation where the horse accepts them calmly on both sides. Personally, I think this is particularly important for starting young horses," Farmer said.
The study, "Visual laterality in the domestic horse (Equus caballus) interacting with humans," was published in the July 2009 issue of Animal Cognition. The abstract is available on PubMed.