Ever get the feeling your horse can read your thoughts? Well, he might not be far off. A new study at the University of Sussex is showing that horses are at least capable of detecting the difference between certain facial expressions in humans.

 “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,” said study co-author Amy Smith, BSc (Hons.), MSc, a doctoral student in the Mammal Vocal Communication and Cognition Research Group at Sussex.

By “socially sophisticated,” the researchers mean that horses live in social groups with a complex communication system that includes the ability to recognize subtle expressions among themselves. Previous research has already shown that horses have a vast range of facial expressions, and that, combined with their body language, vocal expressions, and odors, makes them sensitive to each other’s communication. However, researchers had not yet shown that horses were also sensitive to the facial expressions of other species—specifically, humans—until now.

In their study, Smith and her fellow researchers studied the reactions of 28 riding school horses to photographs of two unfamiliar men, making either angry faces or happy faces. The angry faces caused the horses to look more with their left eye—which has been shown to be related to perceiving negative stimuli. They also had a faster increase in heart rate and showed more behaviors related to stress.

“The reaction to the angry facial expressions was particularly clear,” Smith said.

The horses reacted less to the happy faces, according to the researchers. This might be because as prey animals, the species has evolved to be particularly aware of danger. While they might have an innate ability to recognize negative emotions in humans, it’s also possible that they’ve developed the capacity to recognize the facial expressions associated with anger during their experience with humans. In any case, the researchers said, the important thing is that the horses are capable of distinguishing the emotional expressions in humans, and that they can cause them to react.

“What’s interesting is that accurate assessment of a negative emotion is possible across the species barrier despite the dramatic difference in facial morphology between horses and humans,” added co-author Karen McComb, BSc (Hons.), PhD.

“Emotional awareness is likely to be very important in highly social species like horses—and our ongoing research is examining the relationship between a range of emotional skills and social behavior,” she said.