Horses were shown to read the position of the ears of another horse just like humans read the faces of other humans to know what they are thinking, according to a new study reported in the journal Current Biology. This was the first report on how horses use ear position information in communication.
Animals pay attention to one another. Gaze, or what one is looking at, has often been studied as a measure of how an animal is paying attention to another animal. Studies on gaze have included head orientation and eye direction, but other facial or body characteristics have been largely ignored. Some animals have large and movable ears, and there is great potential for ear movements and positions to have meaning in communications, just like the position and movement of eyes are used for communication in humans. The fact that the eyes of a horse face to the side rather than forward, as in humans, would suggest that gaze judgment in communication must be different.
In the recently reported study, researchers in the School of Psychology, led by Jennifer Watham, at the University of Sussex in Brighton in the United Kingdom created an experimental design to analyze ear and eye positions in horses as a means of communication. They were able to show that one horse transmitted information to another about where food was through the positions of ears and eyes. When the ears or eyes were covered up, this transmission of information did not occur.
In the experiment, photographic images of horses looking at buckets of food were used as visual stimulations to the horses that acted as subjects. The photographic stimuli were life-sized and were object choices in a task designed to learn whether the horse viewing the images knew which bucket they should feed from. The photographic stimuli included horses that had no facial covering, horses that had the eyes covered and horses that had the ears covered.
One of the photographic images was placed on a post between two buckets and the subject horse had to view the image and then decide which bucket they should feed from, according to what the image was communicating. The choice in the experiment was to feed from one of two buckets and the “correct” bucket was the one that agreed with the communication in the image.
When a subject horse viewed an image of a horse that did not have anything over its eyes or ears, the subject horse was more likely able to pick the correct bucket; that is, the bucket that the image horse was looking at. However, when either the eyes or ears of the horse in the image were covered, the subject horse did not pick the correct bucket over expectations of chance. Most significantly, the results showed that ears were a visual cue to the subject horses indicating which bucket they should feed from.
Horses have advanced social relationships and under domestication, often wear devices on their heads. The results from this research study may be very useful in considering what horses wear and whether it allows them to fully communicate using their ears. Another benefit from this research study is if humans can learn to understand what the ear movements of horses mean, then they can understand better what a horse is thinking. The ear movements may not be exclusively useful in horse-to-horse communication, and could be useful in horse-to-human communication as well. The results from this study that showed horses read ear positions to learn what other horses are thinking have important implications for other areas of animal studies.
By Margaret Lutze