Left and right: two horses in one skin

The two sides and what they mean

It used to be believed that horses couldn’t transfer information from one side of their brains to the other, and therefore each side of the brain had to learn separately. This explained why a horse will sometimes spook at a plastic bag when going in one direction, but ignore the same bag when going in the other direction.

However, in 1999 it was discovered that visual information DOES transfer from one side of the horse’s brain to the other (Hanggi: Interocular transfer of learning in horses. Journal of Equine Veterinary Science 1999, if you fancy looking it up.)

So, there must be another explanation for why the two sides seem to respond differently. Recent research indicates that the left is usually the “rapid reaction” side, and the side the horse prefers to have anything it is unsure about or anything to which it wishes to react quickly. It is also the side that is prefered for social interaction between horses, and it’s the side on which most horses learn more quickly. All of these factors are almost certainly connected, and researchers are still working on exactly how. (See the research section for more on this topic).

Given the choice, most horses will put a human on their left, or rather, they will look at the human with their left eye. Many horses become nervous and unsettled when we are on the right, and will try to place us back on the left. The next time someone tells you their horse “won’t lunge”, ask whether it’s in both directions, or only one. Nine out of ten times, they will say “going to the left is OK, the problem is going to the right”.

As we work with out horses, we need to try to even this out until the horse can accept us on both sides.

As the left is usually the horse’s preferred side, we generally recommend starting each exercise on the left, then moving on to the right, but if you find your horse seems more comfortable with you on the right (and there is a small percentage in which the left preference is reversed), it’s fine to start there. If the horse finds the right difficult, stay a little longer on the left, then try again. Don’t force the horse to accept you on the right, but persist gently until it does.

Research has shown that stress increases this tendency to prefer the left, and new aspects to this left/right preference are being discovered all the time. Fascinatingly, it seems that the foreleg the horse moves first when starting off from halt can indicate its state of mind, with the right for being associates with a more optimistic outlook!

Check out the Equine Science talk on the subject!