The team found that when the voice on the speaker belonged to someone the horse knew, the animal would almost always look quickly toward that human, Proops said. | Photo: Photos.com

“We already know that horses can discriminate between different human faces and between familiar and unfamiliar people, but this is the first time we have shown that they can associate the right voices with the right people,” said Leanne Proops, PhD, of the Mammal Vocal Communication and Cognition Research group at the University of Sussex, in the United Kingdom.

In her two-part study, Proops evaluated 72 horses that each heard one of two recorded voices saying the horse’s name over a loud speaker. The two people who had recorded the voices would stand in front of the horse, a few feet apart from each other. In the first part of the study, one person was someone the horse knew while the other was a stranger. In the second part, both people were familiar to the horse. Proops and colleague Karen McComb, PhD, watched to see which way the horse looked when he heard his name spoken over the loud speaker, and how long he looked in that direction.

The team found that when the voice on the speaker belonged to someone the horse knew, the animal would almost always look quickly toward that human, Proops said. And usually, the horse continued to look at that person for a relatively long time. By contrast, if the voice belonged to the unfamiliar person, the horse took a longer time to look at that person and did not look at him or her for very