Research Sheds Light on Equine Long-Term Memory

Remember back when that umbrella popped open and spooked your horse? That might have been five or even 10 years ago, but new research into equine long-term memory (LTM) shows that your horse probably remembers those events just as well as you do.

In a study led by Evelyn Hanggi, MS, PhD, co-director at the Equine Research Foundation (ERF) in Aptos, Calif., horses that had been tested on recognition and advanced learning abilities as many as 10 years earlier were able to repeat the same tasks with a nearly perfect level of accuracy without having to learn the skills again. Not only were the horses able to remember the specific objects learned years ago, they were able to apply those previously learned rules and concepts to never-before-seen objects years later. As the horses had not been exposed to these tests since the time the previous research was completed in 1997, 2000, and 2001, Hanggi concluded that horses have a remarkable capacity for LTM.

Horse in long-term memory trial

A horse indicates the larger of two images.

"Over the years at the ERF, we observed how easily all of our horses recalled certain aspects of our research procedures, such as how to operate the testing apparatus and station," Hanggi said. "We could also stop an experiment and then return to it several months later with no performance loss, and this led us to consider carrying out an LTM study. We were quite excited with the outcome."

In the study, three ERF horses were given three variations of tests in which they had to select between images projected onto an LCD computer screen. The horses were to choose according to criteria established for the previous research on discrimination, categorization, and concept learning carried out six, seven, and 10 years earlier using printed images. "This study also showed that horses are able to perceive images on LCD screens, which had never been previously tested," Hanggi added.

As this initial LTM experiment was limited to only three horses, Hanggi said more research would need to be carried out on a wider scale for conclusions regarding breed or sex differences, if any. "However," she said, "we can now say that excellent LTM is certainly within the capacity of the species."

The study, "Long-term memory for categories and concepts in horses (Equus caballus)," was conducted by Hanggi and Jerry Ingersoll, and was published in the January 2009 edition of Animal Cognition.

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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