When viewing angry facial expressions, the horses showed more stress-related behaviors.
If you own horses or are a horse lover, it can often feel like they can read your mind. Now, for the first time ever, scientists have evidence that horses can distinguish between angry and happy human faces!
The study, published in Biology Letters, explains that the horses’ responses demonstrated an understanding of the angry faces they were seeing. Not only that, they also experienced a physical response — a change in heart rate — something never seen before in interactions between animals and humans.
SEE ALSO: Animal Facial Expressions, Decoded
The psychologists, out of the University of Sussex, studied how 28 horses — a particularly small study size — reacted to seeing photographs of happy and angry human facial expressions. When the horses were looking at angry faces, they turned their head to look more with their left eye — a behavior associated with perceiving negative and threatening stimuli. Their heart rate also increased and they showed more stress-related behaviors.
Interestingly, viewing negative human facial expressions with the left eye has also been documented in dogs, and this is because the right brain hemisphere processes threatening stimuli.
To conduct the experiment, the researchers took large, color photos of the same man making two different facial expressions — either smiling happily and showing his teeth, or frowning and baring his teeth in rage.
They then had volunteers, who were unaware what photos they were holding so they did not change their body language, show the photos to 28 horses across five different stables in the UK between April 2014 and February 2015.
Amy Smith, a doctoral student in the Mammal Vocal Communication and Cognition Research Group at Sussex, who co-led the research said, “What’s really interesting about this research is that it shows that horses have the ability to read emotions across the species barrier. We have known for a long time that horses are a socially sophisticated species but this is the first time we have seen that they can distinguish between positive and negative human facial expressions.”
Amazingly, the horses responded very differently to each facial expression. The horses really did not seem to care when they were looking at the happy photo, but that changed substantially when viewing the negative image.
“This may be because it is particularly important for animals to recognise threats in their environment. In this context, recognising angry faces may act as a warning system, allowing horses to anticipate negative human behavior such as rough handling,” Smith explained.
“There are several possible explanations for our findings. Horses may have adapted an ancestral ability for reading emotional cues in other horses to respond appropriately to human facial expressions during their co-evolution,” said Professor Karen McComb, a co-lead author of the research. “Alternatively, individual horses may have learned to interpret human expressions during their own lifetime.”
This research is part of an ongoing project and the team will continue to study just how well horses can understand our variety of human facial expressions.