Dog Facial Expressions Are Directed at Humans

Brinks the pit bull sits at home smiling at the camera, taken in New York, August 2016.

Few can resist dogs when they raise their inner brows, making their eyes appear to be larger and like those of a human baby who is sad and desiring attention. A study published a few years ago even found that shelter dogs that produced this pathetic facial expression were consistently adopted faster than those that did not.

Dog owners might do well to watch out for this powerful look, because new research suggests that canines tailor their facial expressions for human viewers, and may even intentionally manipulate us with them. 

“There is quite a bit of research showing that human attention affects dog behavior. Our study is one of them,” lead author Juliane Kaminski of the University of Portsmouth told Seeker.

Kaminski, along with colleagues Jennifer Hynds, Paul Morris and senior author Bridget Waller, came to their conclusions after studying 24 beloved family dogs: 13 males and 11 females of various breeds and ages. Before testing started, each dog was allowed to familiarize itself with the human experimenter and the quiet room in which the testing was conducted.

The dogs were next individually brought to the room to a predetermined spot. Each dog was attached to a lead while a female experimenter positioned herself in front of the canine and behaved according to certain conditions. In some instances, she was attentive and holding up food treats that all of the dogs loved. In others, she was attentive, but had no food, or she simply ignored the dog altogether.

As all of these conditions were enacted, a video camera recorded the dogs’ faces. Their facial movements were then analyzed via the Facial Action Coding System (FACS), which was first developed for humans. It identifies observable facial changes associated with underlying muscle movements, permitting an objective, reliable, and standardized measurement of facial movements.

Kaminski and her team found that the dogs produced significantly more facial movements when the experimenter was facing them than when not. Surprisingly, the presence of food had no effect.

Dogs therefore are not only sensitive to a human’s attention when producing facial expressions, but they also appear to be intentionally using these subtle — and sometimes not so subtle — movements to communicate with the viewer.

The findings, published in the journal Scientific Reports, provide evidence that facial expressions of dogs are not always inflexible and involuntary displays reflecting their emotions. Instead, they also often appear to be used for communication, and likely manipulation, too.

“Humans also have the ability to move facial muscles both voluntarily and spontaneously,” Waller said. “So, in some situations we can control our muscles very carefully, and in others, perhaps when we are overcome with emotion, it can be very difficult.”

She added, “In dogs, it is possible that voluntary movement of facial muscles evolved later and in response to selection pressures during domestication.”

Most mammals have a fairly similar set of facial muscles, she explained, but humans and dogs have a particularly complex network of muscles that are capable of producing very slight, as well as very specific, movements. Dogs have some movements that are uncannily similar to those of humans — and their babies.

“But they also have different movements, like ear movements, that humans don’t have,” Waller said. “Other apes, like chimpanzees, also don’t have many ear movements, but numerous monkey species do.”

Mimi the chimpanzee at Chimp Eden in South Africa

The dogs in the study, such as Dusky the basenji and Paul the golden retriever, exhibited an impressive number of expressions. These included pulling their lip corners towards their ears, dropping their jaws, showing their tongues, puckering their lips and much more.

In some cases, the expressions might have been learned from humans. In others, the expressions could hold meanings that are more dog-centric, as for visual cues using additional parts of their body. For example, dogs often lower their front two paws in an unmistakable bow when they want to play.

It could be that dogs use different facial expressions when communicating with other dogs, but the authors are not sure.

“We do not have a lot of research looking at the sensitivity of dogs to other dogs’ attention,” Kaminski said. “We know dogs follow other dogs’ gazes, so they seem to be sensitive to other dogs’ line of sight.”

The researchers suggest it’s possible that horses and goats also attempt to communicate with humans using facial expressions, given that these animals tend to be sensitive to human gazes and levels of attention.

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