Horses often rely on their ears and eyes to communicate with each other, according to a recent study.
The animals' eye direction and their large, mobile ears can be used to tell another horse where to direct its attention, which can be beneficial in locating food and avoiding predators.
The study by Jennifer Wathan, a Ph.D. student at the University of Sussex, is one of the first to examine communication methods that humans lack.
Researchers generally look at communication among animals as they would humans, focusing on communication methods we share, such as body language.
But Watham thought if she looked at the world as a horse would, she might be able to learn more about how these animals share information.
"Horses have really good vision — better than dogs or cats — but the use of facial expressions has been overlooked," she told National Geographic.
Wathan theorized that horses could use their ears to alert other horses to something in their environment, such as food or a predator.
To test her hypothesis, she photographed horses in pasture looking at one of two buckets of food.
One group of horses was photographed as normal, but in one set, the horses' ears were covered by a mask and in another, their eyes were covered.
Wathan then printed the photos so they were life-size images and showed them to horses that were presented with the same two buckets of food.
Her experiment proved that the observing horses were able to recognize that they were seeing another horse in the photo.
Wathan also found that when horses looked at the image where both the horse's eyes and ears were uncovered, they picked the food bucket the horse was looking at 75 percent of the time.
When shown photos of horses whose ears or eyes were covered by a mask, the observing horse chose between the buckets of food at random. However, the horses did slightly better when shown the photo where the horse's ears were uncovered, suggesting ears may play a greater role in horse communication than eyes.