Can Ponies Distinguish Human Facial Expressions? 

This study is the first to document the response of equines that saw happy, sad, angry and neutral facial expressions in person.

A veterinarian stands with a grey horse in a field. Ponies were shown in this study to interpret human facial expressions.
The ponies in the study more often looked at joyous expressions with their right eye, processing the expression in their left brain, which is related to social interactions and learned behavior. iStock

Most humans are good at giving someone a wide berth if they approach with a furrowed brow. But how good are ponies at interpreting our facial expressions? Dr. Katrina Merkies, researcher and associate professor at the University of Guelph, and her team found out in a study involving 20 lesson ponies and some talented actors. 

There has been past research conducted with flash cards. However, this is the first study to document the response of equines that saw happy, sad, angry and neutral facial expressions in person. 

“In terms of behavior generally, the right brain processes emotions and particularly negative stimuli,” explains Merkies. “The left brain is more related to social interactions and learned behavior.” 

Horses see with the left eye things on their left side. They see with their right eye things on the right side. Unlike humans, there’s very little fusion in their optic nerves, and they don’t really have a lot of binocular vision. 

The optic nerve brings information from the eye to the brain. It crosses from the left eye to the right side of the brain and from the right eye to the left side of the brain.  In horses, because their eyes are located on the sides of their head with largely monocular vision, it is easy to discern what they see with their left eye is processed in the right brain and vice versa. 

Methodology and Results

First, researchers conducted initial clicker training with the ponies so they would be likely to approach the human actors. Then, two actors presented expressions of happiness, sadness, anger and neutrality. 

As hypothesised, the angry and sad faces resulted in the ponies looking at the actors more often with their left eye first. The left eye glance corresponds with the right brain, which is in charge of processing negative stimuli. 

Conversely, the ponies more often looked at the joyous expression with their right eye. Interestingly, the neutral facial expression came up with a 50/50 reaction! 

The ponies also had more licking and chewing with neutral faces. They focused their ears more on the actor and stood farther away from joyous or sad expressions. Another action the study noted included heart rate, which was not affected by any of the facial expressions presented. 

Key Takeaways About Ponies’ Ability to Distinguish Facial Expressions

“I think it’s important to note that although the horses did respond to the different facial expressions and they clearly distinguish between them that doesn’t necessarily mean that they understand what we’re feeling or that they feel what we feel,” says Merkies. “They may respond more to an angry face but that doesn’t mean that they feel your anger. And there are other things taken into consideration like the way that you move your body and what else is happening in the environment.”   

Merkies sums up, “Many different cues factor into how a horse will respond in any moment, but understanding our facial expression is important to social interactions. It’s interesting that facial expressions are highly conserved across species, so even though we can have very different physiognomy (we look very different), for example mouse compared to a horse, compared to a human, but facial expressions are fairly similar which is very interesting and very helpful because if you can understand the facial expression from another being or another species, then you can know how to respond appropriately.” 

Further Reading and Education

To visit the research paper, published Sept. 7, 2022, follow this link: https://www.mdpi.com/2076-2615/12/18/2331 

Interesting in learning more about equine behaviour and how horses communicate?

Look for Equine Guelph’s short courses for youth and adults on Horse Behaviour and Safety at TheHorsePortal.ca and more in-depth 12-week courses on Equine Behaviour and Advanced Equine Behaviour

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