Horses have a memory for human emotion, a British study has found, even showing an ability to interpret emotional expressions in photographs.
Researchers found that horses can read and then remember people’s emotional expressions, enabling them to use this information to identify people who could pose a potential threat.
“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,” Professor Karen McComb, from the University of Sussex, said.
Crucially, horses were able to adapt their behaviour accordingly, she said.
“Essentially, horses have a memory for emotion.”
University of Portsmouth researcher Dr Leanne Proops, who was co-lead author of the study, said it was already known that horses were socially intelligent animals.
“But this is the first time any mammal has been shown to have this particular ability. 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 findings of the British study were reported this week in the journal, Current Biology.
The paper, “Animals remember previous facial expressions that specific humans have exhibited”, is authored by a team of psychologists co-led by McComb and Proops, both specialists in animal behaviour.
The research team conducted controlled experiments in which domestic horses were presented with a photograph of an angry or happy human face and several hours later saw the actual person who had exhibited the expression, now in an emotionally neutral state.
This short-term exposure to the photograph of a person’s facial expression was enough to generate clear differences in subsequent responses upon meeting that individual in the flesh later the same day.
The study found that despite the humans being in a neutral state during the live meeting, the horses’ gaze direction revealed that they perceived the person more negatively if they had previously seen them looking angry in the photograph rather than happy.
Previous research, including at University of Sussex, has shown that animals tend to view negative events with their left eye due to the right brain hemisphere’s specialisation for processing threatening stimuli (information from the left eye is processed in the right hemisphere).
Importantly, in the current experiment the humans, who had each been photographed smiling and frowning, did not know which photographs the horses had previously seen, to avoid any risk of behaving differently themselves. Also the differences in reaction only applied to the person the horses had actually seen in the photograph and were not given to a different person.
Although past research, including that conducted by the University of Sussex, has demonstrated that horses can recognise human facial expressions, this is the first time that it has been shown that they can remember emotional experiences with specific individuals. This ability could have clear benefits for social bonding and aggression avoidance when these individuals are encountered again.
“A powerful aspect of our research,” the researches wrote, “is that the horses were not re-exposed to the negative or positive stimuli; rather, they were presented with the neutral person who was blind to the valence of the photograph that subjects had previously seen.
“Thus, the results could not be due to emotional contagion; i.e., the subjects could not be picking up on the emotion expressed by the live human model.
“Instead, our results suggest that the subjects (horses) were using a memory of the positive or negative expression in the specific human previously seen to guide their response to that same person even when they adopted a neutral expression.”
They continued: “Our paper provides direct evidence of a key role for processing of facial cues to emotion in long-term social functioning in a non-primate, throwing light on its adaptive significance across species and indicating that facial expressions can be registered and remembered even in inter-specific communication.”
Animals Remember Previous Facial Expressions that Specific Humans Have Exhibited
Leanne Proops, Kate Grounds, Amy Victoria Smith, Karen McComb.