Listen Up: Horses Demonstrate Auditory Laterality

A neighborly neigh is processed in a different way than other whinnies, meaning that horses have brain side preferences for sounds, according to a new study by French researchers.

The phenomenon, known as "auditory laterality," has previously been shown in humans, dogs, and some other vertebrates. But this new research is the first to reveal auditory laterality in ungulates, or hoofed animals.

Whereas the left hemisphere is clearly dominant for the processing of sounds that are familiar and normal, such as whinnies from nearby neighbors, both sides of the brain deal with sounds that are new or which emit an emotional response, according to the researchers. This could be a whinny from an unknown horse or one from the same social group, respectively.

Horse listening test

Students Sarah Boivin and Haifa Benhajali record which ear the horse uses to listen to whinnies and other sounds.

"It was clear in our studies that horses do not have the same level of attention when they hear a horse they know compared to a horse they don't know," said Alban Lemasson, PhD, professor-researcher in the Animal and Human Ethology Laboratory at the University of Rennes and co-author of the study.

Twelve study horses were tested with iPod recordings of various whinnies played back at a distance of 10 meters (30 feet) behind the horse. The recorded whinnies represented three groups: members of the horse's social group, nearby neighbors not in the horse's immediate social group, and strangers completely unknown to the horse. A fourth test was made using white noise as a control. The horses showed a strong preference for turning their right ears (a left-hemisphere response) to listen to the neighbors' whinnies. The other whinnies caused the horses to listen with either the right or the left ear without a specific preference. The white noise rarely resulted in any reaction from the horses at all.

As equine auditory laterality preferences would probably also apply to human sounds, knowledge of the phenomenon could help improve communication between humans and horses, Lemasson said. However, further research with a greater number of horses must be carried out before any conclusions can be made.

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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