Social animals communicate in a variety of ways; from gestures to facial expressions, touch to vocalizations. Like humans, studies on various non-human primates such as chimpanzees have demonstrated that these animals can convey a lot of information through gaze and head position. But what about animals with very mobile ears and side-facing eyes, such as horses? Can they use ears and eyes as visual cues to attention? While that may seem a “yes, duh,” to horse owners, no one had actually ever studied this form of communication in horses before. Now, a team of scientists from the University of Sussex have stepped in to put suspicions to the test. Their study can be found in Current Biology.
For the study, researchers photographed horses whilst they were paying attention to something. They then displayed these life-sized photographs above two buckets of feed in such a way that the image of the horse appeared to be paying attention to one of the two buckets. In order to investigate which areas of the face were important in providing information, the researchers manipulated the photos by covering up either the eyes or the ears with masks. Next, they released a number of horses, one at a time, and allowed them to decide which bucket to feed from.
The researchers discovered that the horses were sensitive to the attentional state of the horse in the photograph, and that this influenced their decision of where to feed. If the horse in the image was not obstructed by the masks, the study horse was more likely to choose the bucket that the image appeared to be paying attention to. If the eyes or ears were covered, however, the choice was found to be random.
Another interesting finding was that the ability to detect cues varied depending on the identity of the horse in the image, indicating that differences in facial features or expression may be important.
The researchers conclude that a combination of head orientation and facial expression using the eyes are ears is necessary to communicate social attention. This study therefore challenges previous ideas that animals with eyes on the side of the head cannot gather information based on the direction of one another's gaze. They would like to take this work forward by exploring facial features related to the expression of emotion in horses.
“Horses display some of the same complex and fluid social organization that we have as humans and that we also see in chimpanzees, elephants and dolphins,” lead author Jennifer Wathan said in a news-release.
“And the more we look at communication across different species, the more we can consider what might have promoted the evolution of sophisticated communication and social skills,” she told the BBC.
[Header image "horses in the wild," by efilpera, via Flickr, used in accordance with CC BY-NC-SA 2.0]