SUSSEX, England —Â Some people never forget a face. Apparently, neither do horses. A study by researchers at the University of Sussex and the University of Portsmouth found that horses can remember the facial expressions of people they’ve seen before.
The researchers believe horses use this ability to discern people who might be a threat to them.
For the study, the authors showed domesticated horses a photograph of an angry or happy human face. A few hours later, the real person seen in the photograph would interact with the horse in an emotionally neutral state. The horses showed distinct differences in subsequent responses when meeting the individual in person later the same day.
“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 behaviour accordingly,” says Sussex professor Karen McComb in a statement. “Essentially horses have a memory for emotion.”
Even though the humans meeting the horses in person were in a neutral state during their interaction, the direction of the horses’ gaze proved to the research team that they perceived the person more negatively if they had seen a photo of them looking angry than if they saw a photo of the person looking happy.
The researchers were able to tell how the horses perceived the humans in their live meetings from previous research, which showed that animals usually view negative events with their left eye because of their right brain hemisphere’s specialization for processing threatening images.
“We know that horses are socially intelligent animals, but this is the first time any mammal has been shown to have this particular ability,” says co-lead author Dr. Leanne Proops. “What’s very striking is that this happened after just briefly viewing a photograph of the person with a particular emotional expression – they did not have a strongly positive or negative experience with the person.”
The study was published in the journal Current Biology.