The research follows previous work by the team from University of Sussex which compiled a directory of horse facial expressions, and revealed that Black Beauty can read your emotions – a phenomenon also seen in dogs.
“We knew that horses could register emotional expressions, so we wanted to know if they could remember them, so that they can actually use those memories to guide their future interactions with specific individuals,” said Karen McComb, co-author of the study and professor of animal behaviour and cognition at the University of Sussex.
McComb and colleagues analysed data from 11 horses who had been shown a photograph of a human pulling an angry face and 10 horses shown a picture of a human smiling.
Each horse was shown a large photograph of one of two participants for two minutes; three to six hours later they were brought face-to-face with the person they had seen in the photograph who was sporting a neutral expression. To avoid the possibility of giving tell-tale cues, the person was unaware whether it was a happy or angry photo of that had been previously shown to the horse.
The small study, published in the journal Current Biology, reveal that horses who had been earlier been shown an angry photo of the participant spent longer viewing them with their left eye than those who had seen a happy photo.
That, said McComb is important because information from the left eye is sent to the right hemisphere of the brain, where potential threats and dangers are processed. By contrast, those who had seen the happy photo spent longer looking at the person with their right eye than those who had seen an angry image. “The left hemisphere of the brain connects to the right gaze and is more specialised for prosocial, positive-type reactions,” said McComb.
The team also found that horses which had earlier been shown an angry photograph appeared to find the face-to-face meeting more stressful, more frequently displaying “coping behaviours” like licking and chewing, scratching, and sniffing at the floor.
To see whether the results were a response to a particular person, the team showed 24 different horses a happy or angry photo of one of two participants and, later that day, brought them face-to-face with the other participant. “They treated the person the same irrespective of whether it was the negative [photograph] they had seen in the morning or the positive one,” said McComb, although she noted that in both cases the horses spent longer looking with their left eye, possibly indicating they weren’t keen on the experimental setup.
The upshot, say the team, is that horses appear to be able to remember facial expressions of specific humans, even when only seen for a few moments – and from a photograph.
“It is quite an amazing result really,” said McComb. “It is really interesting that animals are picking up on the subtle emotional expressions that humans are revealing on a moment to moment basis” she added. “Crucially in taking it in they don’t just forget it, they use that information – they have a memory for the emotional states that they have seen in humans and they use that information.”
The team note that it is not clear whether horses can also read the expressions of other species, too, or if they are particularly tuned into humans – possibly as a result of domestication – either through an innate or learned ability.
Paul McGreevy, professor of animal behaviour and animal welfare science at the University of Sydney, who was not involved in the study said the research highlights the importance of social bonding in horses. “These exciting findings explain how horses have evolved a remarkable ability to see objects and other beings in great detail to help avoid conflicts within their social group and remain safe from threats in their environment,” he said.