Dog owners will never tire of gazing into the gaze of their canine companion, but this fascination might just be one-sided. A study tells us that the brains of dogs place as much importance on a human’s face as they do on the back of their skull.
The brains of humans and other non-human primates have evolved to process faces, which play a fundamental role in verbal and non-verbal communication. Previous research have already suggested that dogs can also maintain eye contact and even read our emotions through our facial expressions, but are dogs brains wired to focus on faces the same way humans are? The question remained open.
To find out, researchers from the Department of Ethology at Eötvös Loránd University in Hungary carried out several experiments.
As part of this work, published in the journal JNeurosci, the researchers used functional magnetic resonance imaging (fMRI) to measure the responses of twenty companion dogs to faces. The dogs were trained to stay still inside the machines, resting their heads on a chin rest while looking at a screen.
The scientists then presented them with four types of clips, each lasting only two seconds. These videos showed either the front or back of a human head, or the front or back of a dog’s head. The faces shown had a neutral expression and all looked away to make sure the dogs didn’t feel threatened.
In parallel, thirty human volunteers carried out the same experiments. During this time, the researchers studied the brain activities of each participant.
Unsurprisingly, the human participants were captivated by every face (human and canine). Much of their visual system indeed became active. Conversely, these brain regions were quieter when these same participants looked at the backs of their heads.
Surprisingly, the parts of dogs’ brains that process vision, on the other hand, didn’t seem to care. No area of the brain was activated more when viewing a human face compared to the back of the head. It also emerged that from a cerebral point of view, dogs reacted more to the vision of other dogs. This is a point they shared with the human cohort who also preferred the faces of their own species.
There are thus similarities and differences. The fact that humans and dogs each respond more to the vision of their own species raises the idea of an important organizing principle in the mammalian brain for processing social stimuli. In terms of differences, the study found no brain areas in dogs capable of encoding whether the image seen is a face or the back of a skull, while in humans, it is a crucial distinction.
“In other words, in dogs, conspecific preference passes above facial preference, while in humans, facial preference passes above conspecific preference,” the researchers write. “This is an essential difference.”
While our pets’ brains aren’t ultimately wired to prefer our faces, previous research has obviously shown that dogs recognize and love their owners. Our pets may also be attracted to our scent or the sound of our voice. Moral of the story: your dog doesn’t care about your appearance, he or she loves you anyway!