Eyes are the mirror of the soul – also for dogs

A cute border collie eagerly enters a small experimental room. It immediately lies down on a mattress in front of a 22 inches LCD monitor and starts watching a set of photos. The dog seems to be watching the screen with an interest! It even waves its tail from time to time; perhaps because it has learned that after a short while, a quiet clicking sound will be played and a tasty dog cookie will fall on the ground behind the mattress. It will be a well-deserved reward for the obedient dog.  To make sure that the fluffy canine does not move too much while watching the photos, the experimenter has trained it to place its chin on a special support which looks a bit like an adaptation of a wooden kitchen step.


No, I did not make it all up as a scientific variation of the cute animal videos that overpopulate YouTube. You can see this scene with your own eyes in a supplementary video to a paper  published recently in PLOS ONE. The publication presents the results from a group of scientists from the University of Helsinki who wanted to examine how dogs look at faces of other dogs and of people, especially when these faces express different emotions. So they trained 31 dogs to look at the LCD screen and used the eye-tracker to reliably measure where the dogs were looking.

Eyes first

They found out that dogs examine faces of other dogs the same way as we examine faces of other people. They first look at the eyes, then the middle part of the face just to finish the observation by looking at the mouth. By doing so, they behave exactly like humans, chimpanzees, gorillas, orangutans and macaques. As all these other species, dogs look for the longest portion of time on the eyes, or just next to them. We know from previous studies and personal experience that people also prefer to look at the eyes when looking at faces. In the context of human interactions, we say metaphorically, that the eyes are the window to the soul. The authors conclude that, also for the dogs, eyes convey essential information for the understanding of the emotional facial expression.

Man’s best friend

But can dogs “read” emotions from human faces? The authors argue that this is exactly the case. When dogs look at the photos of human faces, their eye-movements follow exactly the same pattern as when they look on the dogs’ face. The dogs first look at the eyes, then the middle part of the face and finally at the mouth. They also react differently depending whether the photo shows a happy or angry human expression. The authors speculate that the ability to read and communicate emotions between our species gave the dogs an advantage during the process of domestication. It is no wonder that dogs became “man’s best friend”.

Would you like to watch the video? To see the actual video featuring dogs performing the experiment, go to the online version of the paper, scroll down to the “Supporting Information” section, and have a look at the “”S1 Movie”. Enjoy!

2 thoughts on “Eyes are the mirror of the soul – also for dogs

    1. Yes, indeed, videos help us understand the methods. It was fun to watch (I simply love the first dog!) but it also helps to replicate the experimental conditions in the future experiments.

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