Rowdy was the equine love of my life. Every time I went to the barn, I was smiling because I was so ridiculously happy. I couldn't help giddily throwing my arms around his neck, whether I was brushing him, riding him or cleaning his stall. A lot of horses wouldn't put up with those shenanigans, but Rowdy was kind of a big, sorrel dog who knew I was smitten.

He nickered when I bounced into the barn and rubbed his head on me, frisking me for carrots. Horse people will always tell you that horses sense emotions, especially fear. But I'm convinced they can also tell when you just think they're amazing.

Now a new small study, published in Current Biology, says not only can horses sense human emotions, they can also read human expressions and remember them for later.

Researchers at the universities of Sussex and Portsmouth in the U.K. held experiments in which domestic horses were shown large photos of either an angry or a happy person. Several hours later, the horses met that individual in person but with a neutral expression.

Despite the person's neutral stance, the horses responded based on how they saw the individual in the photo, turning their gaze in a specific direction in response.

Earlier research found that animals tend to look at negative or threatening events with their left eye because information from the left eye is sent to the right hemisphere of the brain, where possible threats and dangers are processed. Horses tend to look at more positive things with their right eye. And that's what happened here.

When horses saw the person they had seen frowning in the photograph, they spent more time looking with the left eye. They also showed more stress-oriented coping behaviors such as licking, chewing and sniffing the floor. But when the horses saw the person they had seen smiling in the photo, they spent more time looking with the right eye.

A memory for emotion

Mary Jo and Rowdy The author with her beloved Rowdy. Note the smile. (Photo: David DeNoma)

Importantly, the people who encountered the horses for the study had no idea which photo the horses had seen earlier so they couldn't give any involuntary cues to the animals.

"What we've found is that horses can not only read human facial expressions but they can also remember a person's previous emotional state when they meet them later that day — and, crucially, that they adapt their behavior accordingly," Professor Karen McComb from the University of Sussex said in a statement. "Essentially horses have a memory for emotion."

The horses seemed to have made a snap judgment call on the person based only on the expression in the photo.

The researchers believe having this ability helps horses with social bonding and avoiding possible aggressive encounters.

"It is quite an amazing result really," McComb told The Guardian. "It is really interesting that animals are picking up on the subtle emotional expressions that humans are revealing on a moment to moment basis. Crucially in taking it in, they don’t just forget it, they use that information — they have a memory for the emotional states that they have seen in humans and they use that information.”

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.