Professor at Leiden University

Truly a (Wo)man’s Best Friend – Emotion Recognition in Animals

It is no secret that pet owners are convinced that their pets recognize and act on their owners’ emotions. Often we’re right… but not always.

Many of us relate to the feeling that our pets recognize our emotions. We think that they come to us when we are sad, to comfort us; and we are happy when our pets respond more enthusiastically to us than they normally would. While the non-animal lover might be skeptical, there may be some truth in the animal-lovers’ sentiment.

Recent studies have shown that horses, dogs and cats can at least to some extent recognize human emotions. These findings are remarkable, as previous studies suggested that inter-species emotion recognition was only found in humans. In one study, which was published only last month, horses were presented with a picture of a happy and an angry human face. The horses were more likely to look at the angry face with their left eye. This is, according to the researchers, because the right hemisphere of the brain, to which the left eye sends the incoming information, is specialized in handling threatening stimuli. Furthermore, the horses’ heart rate increased when they saw the angry face compared to the happy face. This is something we, as humans, can relate to: when something scares us, our hearts start to beat faster as well, due to the release of adrenalin in our bodies, which prepares our bodies to either fight with or flee from the stimulus that scared us.

Dogs can also recognize emotions in human faces and show the same bias as horses when it comes to negative stimuli (like angry faces): they tend to look at them with their left eye, to process it with the right hemisphere of their brain. A second study, published in January, revealed that when dogs were presented with a positive or negative emotion on human faces, accompanied by a vocalization of either the positive or negative emotion, dogs looked longer at the faces with the right sound. This indicates that the dogs were able to match the right sound with the right visuals and that they are able to differentiate between emotions in humans.

The studies also try to answer the question of how it is possible that horses and dogs can recognize human emotions. For the horse, it is possible that horses transferred their ability to recognize emotions in other horses to recognizing them in humans. This helped them survive and thrive during the co-evolution of the two species. A second possibility is that horses learn from repeated exposure to distinguish human expressions in their lifetime. For dogs, a similar reason is given: being able to recognise emotions in humans might have given those dogs an advantage. They would have been better adapted to humans and therefore more likely to survive when domesticated.

People might rejoice with the idea that their pets recognize their emotions, but before cat lovers jump in the air of joy – because they can finally convince everyone that cats are not selfish and do care about their owners – this study (sadly) shows that cats do not recognize emotions in humans to the extent that horses and dogs do. The research found something that hints at some emotion recognition: cats spent more time with their owners when the owners were happy. If you are wondering why: when you are in a happy mood, you are more likely to give your cat treats. Cats have come to realize this and therefore like to spend more time with you when you are happy. Unlike dogs and horses, it is possible that only interacting with humans is not enough to enable cats to truly ‘read’ our emotions. This opens up questions about horses and dogs as well: what do they then have that cats lack? But, do not despair cat lovers: while this study seems to show that cats might just be selfish, other studies could reveal something different.

One last note: it is important to realize that being able to recognize emotions is different from acting on those emotions. Therefore, pet owners who are convinced that their pets are able to recognize and act on their emotions are (now) only partially right: while the studies prove that horses and dogs are able to recognize emotions, they did not yet prove that they also act on this recognition. But the field is young and a lot more research can still be done. Who knows what that might be able to tell us about our furry friends.

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