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Horses share a close relationship with humans in their daily lives. Domesticated over 5,500 years ago, they, like dogs, are attentive to humans and their behavior. Moreover, they are very social animals, living in large, stable groups in the wild. Thus, one would expect horses to have developed sophisticated social abilities to cope with the complex relationships they can form.
Researchers put these abilities to the test in a recent study published in Animal Cognition. The work was led by Léa Lansade, a researcher in ethology at the Institut Français du Cheval et de l'Equitation (IFCE), and graduate student Miléna Trösch, and was carried out in the team Cognition, Ethology, Welfare of the INRAE.
Lansade and her colleagues wanted to see if horses engaged in "social eavesdropping," in which an individual learns about their group mates simply by watching them interact together. They designed an experiment to test whether horses could attribute a positive or negative valence to a person by observing the behavior of that person towards another horse.
The researchers showed horses two videos. One displayed a positive interaction between an experimenter and an unfamiliar "actor" horse (a grooming session). The other showed a negative interaction (an unpleasant veterinary act involving ear ointment and a small spray towards the head). The researchers collected behavioral and physiological measurements from the horses as they watched the videos to see if the horses could perceive the emotional content of the scenes.
“The difference in reactions to the two videos was really stunning: just by watching these reactions, we could guess which video the horse was looking at,” says Trösch.
When watching the negative video, the horses showed signs of negative emotions, such as taking on a vigilance posture and an increased heart rate. The horses were more relaxed when watching the positive video, with a posture typical of positive emotions in a grooming context—even extending their lips and attempting to reciprocate the grooming to the assistant holding them!
The horses expressed the same emotions as the actor horse seen in the videos, which Trösch says suggests emotional contagion. Emotional contagion is the automatic triggering of one’s emotion caused by observing the emotion in another individual, like “catching” an emotion.
“Emotional contagion increases group cohesion and the synchronization of behaviors,” says Trösch. “For instance, if one individual of the group perceives a threat, his fear will spread to the whole group, and they will run away together—even the group members that did not directly perceive the threat.”
After watching the videos, the horses were presented with a choice test, facing the positive and negative experimenters in real life. The horses successfully discriminated between the two experimenters, but in an unexpected way: They touched the negative experimenters more than the positive ones.
Trösch and her coauthors say that this counterintuitive result may reflect appeasement behavior on the parts of the horses. They may have interpreted the negative video as a conflict between the horse and the human. Similar behavior has been recorded in bonobos towards negative or badly behaving experimenters.
Together, the results suggest there is emotional contagion in horses, which is considered a building block of empathy. Trösch and her colleagues are next interested in whether horses are capable of other empathic responses, such as attempting to console an individual who is sad. They would also like to test whether horses can use social eavesdropping in different contexts; for instance, if a horse is more likely to help a horse (or a human) who previously helped another horse.
Furthermore, Trösch says their results have direct practical implications for horse welfare and management.
“As horses can attribute a valence to people indirectly by watching them interact with other horses, it means we have to pay attention to what they see,” she says.
“For instance, in the case of veterinary practices that are unpleasant, it might be better to conduct them with no other horse watching; otherwise, the other horses might attribute a negative valence to the vet, potentially complicating future encounters with them.”
In other words, when working with horses, it’s just horse sense to consider their social smarts and emotional reactions.
References
Trösch, M., Pellon, S., Cuzol, F., Parias, C., Nowak, R., Calandreau, L., and Lansade, L. Horses feel emotions when they watch positive and negative horse–human interactions in a video and transpose what they saw to real life. Anim Cogn (2020). https://doi.org/10.1007/s10071-020-01369-0.
