Why would a horse stare into an arena mirror? Research from Italy suggests that he’s trying to get a good look at himself.

The new study, conducted by a group of researchers at the University of Pisa, confirms earlier speculation that horses can, in fact, recognize themselves in a mirror. Many species, including elephants and dolphins, are presumed to also possess this ability. But cognitive self-awareness is difficult to test and until now had only been validated in some primates.

In a 2017 pilot study, the Italian group gave horses the mirror self-recognition (MSR) test, considered the “gold standard” for determining if a subject is self-aware. For the test, colored marks were placed on the cheeks of horses that were visible to them only when they were in front of a mirror. If a horse attempted to rub the mark from his face after seeing his reflection, this was considered a sign of self-recognition.

The findings suggested that the subject horses could indeed recognize themselves, but the limited size of the trial and the questions about its methodology kept the researchers from drawing a definitive conclusion.

Now, however, the same group—Paolo Baragli, DVM, PhD, Chiara Scopa, Veronica Maglieri and Elisabetta Palagi, PhD—has repeated the experiment using more horses and slightly different methodology and the results confirm the earlier findings.

For the study, 14 horses were individually confined in an enclosure for 30 minutes under four different scenarios, one per study day: First, a mirror was placed in the enclosure to acclimate the horse to its presence, but it was positioned so the reflective surface was not visible to him. In the next stage, the mirror was shifted so the horse could see his reflection. Then, an “invisible mark” was made with clear gel on the horse’s cheeks before he was returned to the space with the uncovered mirror—this was to ensure the horses reacted to the sight of the marks rather than the sensation of the gel on their skin. In the final stage, colored marks, made with odorless yellow or blue paint, were placed on the horse’s cheeks in locations visible to him only in the mirror, before he was returned to the space with an uncovered mirror.

The researchers monitored the horses during each phase, looking for behaviors such as moving in an out of the sight of the mirror— “peek-a-boo”—or sticking out their tongue to confirm that their movements were being reflected.

“Both peek-a-boo and tongue protrusion are contingency behaviors, along with looking behind the mirror and performing head movements in front of the reflective surface,” the researchers explain, noting that prior to the experiment none of the horses has been exposed to mirrors. “These are highly repetitive or unusual movements performed only when animals are in front of the mirror, probably to verify if the movements of the image in the mirror match their own movements. Individuals belonging to species which successfully passed the mark test performed these kinds of behaviors.”

The researchers then noted whether the horses tried to remove the colored markings by rubbing their faces against their legs when they saw their reflections in the mirror. Doing so would indicate the horses knew that the marks, which were visible only in the reflection, were on their own faces.

The data showed that nine of the 11 horses attempted to rub the colored marks off their cheeks after looking into the mirror, while only five out of the 11 horses attempted to rub the invisible marks from their faces. Horses spent more time rubbing their faces and less time scratching other areas of their bodies when the colored marks were present. What’s more, the study horses who rubbed the colored marks also performed at least one of the “contingency behaviors” such as peek-a-boo. All of this, the researchers conclude, suggests the horses possessed cognitive self-recognition.

They emphasize, however, that this finding isn’t surprising, given the highly developed social and emotional lives of horses. “Mirror self-recognition, which is a building-block of self-awareness, provides information about the cognitive and emotional skills that are necessary to develop complex social relationships and to engage in behaviors relying on different levels of empathy,” the researchers explain.

“Horses are able to integrate different sensory systems to individually recognize both other horses and humans as well; they also can combine different facial cues of other horses to gather information on the environment,” they add. “Moreover, horses can communicate their emotions and understand facial expressions of both horses and humans. Finally, they reconcile after conflicts and engage in triadic post-conflict reunion to maintain the social balance. Taken together, these findings are indicative that horses, like other highly cognitive social animals, show some degree of awareness, which implies the ability to assess the significance of a situation according to both the social environment and the self.”

Reference: “If horses had toes: demonstrating mirror self recognition at group level in Equus caballus,” Animal Cognition, March 2021

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