Dogs blink at each other a lot, and a new study suggests this behavior is more than just a way to keep their eyes clean: it's playing an important role in canine body language.
In her career as an evolutionary biologist, Chiara Canori from the University of Parma in Italy has found dogs blink more around other dogs, and even around humans, than they do outside these social interactions.
But to find out whether these blinks really are sending signals, she led a research team in setting up a kind of scientific movie night for a whole bunch of pet pooches.
Each of the 54 participating dogs sat with their owner through a movie session where they were shown three different videos of other dogs blinking, nose-licking, and being attentive while still. Between each genre of movie, they were given a 5-minute break to recover from whatever reactions they might have had to this viewing.
The face signals were performed by a trio of canine actors – a 6-year-old terrier mix, a 5-year-old cocker spaniel mix, and a 1-year-old border collie mix. A pilot study ruled out the identity of the dog in the clips influencing audience attention, as well as the kind of expression the dogs performed.
Previous studies have suggested that a dog licking their nose indicates either positive anticipation or frustration – which, as anyone waiting for their food order to arrive will know, are closely situated in the neighborhood of emotions.
To measure the dogs' responses to their canine comrades blinking, the team kept track of the audience's heart rates throughout the movie viewing, in the hope it might offer some sense of their emotional reaction or at least how aroused or relaxed they were.
The fact all heart rates remained stable throughout the viewings doesn't tell us much about the emotional nuances of the perceived facial signals, but it does suggest the audience's reaction wasn't affected by any ambient stress.
As Canori and team suspected, the audience dogs blinked significantly more frequently while watching the ‘blinking' clips compared to the nose-licking ones. There was a similar pattern when comparing the blink videos and the attentive still videos, but those results weren't statistically significant enough to tell us anything.
This implies a mimicry phenomenon, a bit like when someone yawns nearby (or even mentions it) and for some reason or other – wait for it – you can't help but yawn back.
And we primates actually do subconsciously communicate via blink, too: next time you're talking to a friend, you might notice that we humans tend to synchronize blinks with our social partners, particularly during breaks in speech or when we've finished talking.
It's possible that dogs' blinking behaviors also play a role in their communication, something we already know is an important part of cats' social lives. And this research adds further evidence to that fact.
“In dogs, blinking has been considered as an appeasement behavior used to express non-aggressive intentions towards conspecifics,” the authors write.
“Reciprocal blinking in dogs might help to facilitate conspecific social bonds, cope with frustration and communicate non-aggressive intentions, as already shown in the interspecific context with humans.”
But before you go batting your eyelids at all the canines in your life, keep in mind we're not really sure what this blinking behavior actually means to dogs: just that it probably means something.
At least one prior study found blinking in dogs is associated with frustration, and as with any non-verbal communication, there could be subtle nuances we haven't begun to broach. If human yawns can signal moods ranging from empathy to boredom, dog blinks may too contain a broad pallet of emotion we're yet to translate.
This research is published in the journal Royal Society Open Science.
