Researchers Study Horses' Facial Expressions

Researchers Study Horses' Facial Expressions

The study authors said horses have a “rich repertoire of complex facial movements,” many of which are surprisingly similar to humans.

Photo: iStock

If you’re happy and you know it clap your … hooves?

While horses might not be clapping in tune to that emotionally expressive song, it does seem that if they’re happy and they know it, their faces will surely show it. Recent study results suggest horses are capable of a wide range of facial expressions that aren’t so different from those of humans and chimpanzees.

And though the horses probably won’t be “smiling,” per se, they do still have a “rich repertoire of complex facial movements,” many of which are surprisingly similar to humans, said lead study author Jennifer Wathan, PhD candidate, researcher in the Mammal Vocal Communication and Cognition Research at the University of Sussex in the United Kingdom.

However, just because horses have similar facial expressions doesn’t mean those expressions necessarily represent the same emotions that they do for people, she added. Determining the association between expressions and feelings is an upcoming project for Wathan and her team. But first it was essential to determine exactly what expressions horses are capable of making.

“The thing about facial expressions is that they are really difficult to describe accurately,” Wathan told The Horse. “This is partly because we perceive facial expressions as whole pictures, where numerous images are assigned to a category--for example, an emotion like anger.

“However, facial expressions are not given as such clear signals, but instead they can be composed of numerous different movements, which overlap in a complicated sequence, like language,” she said. “This makes them really challenging to accurately describe and record.”

But record them she did. Her team’s work resulted in the first “EquiFACS”—developed based on the facial action coding system (FACS) that already exists for humans, primates, and dogs. The FACS and EquiFACS describe very precise, often subtle facial muscle movements that, when combined with other movements, can create what we know as an “expression.”

We already know that horses exhibit specific facial expressions to express their taste preferences and pain levels, but Wathan’s study was the first to document the full scale of possible equine facial movements. She published her EquiFACS research report, along with multiple photos and videos as examples, as a free-access online resource.

Getting an accurate equine FACS required an innovative muscle dissection method the researchers called the “face mask.” Whereas previous dissection methods called for removing the skin from the muscles, Wathan and her professor Karen McComb, PhD, also of the University of Sussex, determined that separating the skin would be detrimental to their purposes. Instead, they separated the superficial facial muscles from the deeper muscles of the head, keeping that superficial network attached to the skin. That way, they were able to not only maintain the integrity of these smaller muscles, but also able to see how they were connected—in particular with the skin—and how they could interact with each other.

After carrying out a “face mask” dissection of one horse head, the research team then closely observed 15 hours of video footage of 86 horses in a variety of natural settings interacting with other horses, humans, and some other species such as dogs. Based on the dissection results and observations, they developed a complete list of specific facial actions (17 “action units”) that could make up various equine facial expressions. (For comparison’s sake, researchers have found 27 action units in FACS for humans, but only 13 for chimpanzees and rhesus monkeys. For dogs, they’ve found 16, and in cats—with extensive whisker and ear movements—they’ve found 21.)

With that list—the EquiFACS prototype—the researchers then asked four people to watch videos of the horses and record what they saw using the EquiFACS. Three of these people had no experience with any kind of FACS, and one of them had never even had any experience with horses. But despite this inexperience, the researchers judged their average accuracy rate at 86%, suggesting that the EquiFACS is not only a reliable tool but one that’s easy to use, as well.

What does that mean for the horse? The researchers said—once they’ve determined what sentiments those expressions actually represent—the EquiFACS could lead to better health care, welfare, and management of their social and working lives as humans learn to better read the expressions on their horses’ faces.

“Training (people) is a large element of what we would like to do with EquiFACS, as it does offer us the opportunity to make sense of these complex expressions that are otherwise difficult to describe,” Wathan said.

She said the research could even lead to better depictions of horses in art. “We’ve even had a computer animator speak to us, and he is using EquiFACS to inform a horse animation that he is currently producing,” she said.

Wathan’s group’s next goals are to better understand what these facial movements mean, without projecting our own human readings into the interpretation. How are they going to do that? They’ll ask the horses. Cautioning that the ongoing research is still too confidential for giving out details, she told The Horse that they’re essentially “asking horses to judge the faces of other horses, rather than us making human-based observations/judgements.”

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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