Some people notice that their horses usually put people on the left. This has traditionally been attributed to training practices, and that may be part of the story, but it’s not all of it.

When my mentor, Richard Thompson, pointed out to me that this is not just a training habit, but that the horse makes an active choice to put the person specifically in its left eye, I suddenly began to see that this preference manifests itself in all sorts of ways and even seems to vary from one situation to the next.

So, I set about my first research project which tested whether this preference is trained by  comparing groups of horses that had either been traditionally trained (predominantly from the left) with those that had been bilaterally trained (equally on the right and left) and in both groups the horses showed a preference for putting the person on the left.

We looked at the horse’s choices when going past a person to reach a feed bucket, as well as their preferences when approaching a person in an “at liberty” situation

Although I studied psychology at university, that was a long time ago, and my research techniques were decidedly rusty! Luckily it all worked out thanks to the invaluable help of Professor Konstanze Krüger, one of the world’s few specialist equine researchers, and one of my old tutors at St Andrews University, Professor Richard Byrne.

This was the first study I authored on this topic, and the first to look at equine laterality in interactions with humans. The left eye preference found here, combined with other studies which found the left eye to be preferred for negative associations, led to much discussion as to the significance of the “person on the left” preference.

A follow up study we conducted in 2016 showed that among horses and ponies themselves, there is a preference for left side social interactions such as grazing, fly swishing, mutual grooming and so on.

The strength of this left preference is similar to that shown for aggressive interactions in semi-wild horses, and is has also been found that horses react more quickly and more strongly to a startling event (an umbrella opening suddenly) when it is presented on the left.

So, there are many pieces to the puzzle, and we are still trying to work out how this difference between the left and right works, and why it exists.  However, it is safe to say that the majority of domestic horses and ponies prefer to have us on the left, and this means that this is usually the better side to start when working with your horse on the ground.

 

Visual laterality in the domestic horse (Equus caballus) interacting with humans

Kate Farmer,  Konstanze Krueger, Richard W. Byrne.  Animal Cogn. 2010 Mar;13(2):229-38. Epub 2009 Jul 17 

Original article

Sensory laterality in affiliative interactions in domestic horses and ponies (Equus caballus)

Farmer, K., Krüger, K., Byrne, R.W. et al. Anim Cogn (2018) 21: 631.

Original article

Asymmetry of flight and escape turning responses in horses.

Austin NP, Rogers LJ (2007) Laterality 12(5):464–474. https ://doi.org/10.1080/13576 50070 14953 07

Lateralization of agonistic and vigilance responses in Przewalski horses (Equus Przewalskii)

Austin NP, Rogers LJ (2014). Appl Anim Behav Sci 151:43–50. https ://doi.org/10.1016/j.applanim.2013.11.011