Dogs pay close attention to our faces. They can react to our gaze, certain expressions or our attention. But eye blinking is much more subtle. Researchers from the University of Parma, Italy, wanted to find out whether this nearly automatic movement could also matter during an interaction.
The experiment involved 35 dogs of different breeds. Each one watched videos successively showing its owner, an unfamiliar man and an unfamiliar woman. In a first 40-second sequence, the people blinked every three seconds. In another, they simply looked ahead without blinking. The researchers then carefully counted the dogs’ eyelid movements.
The difference was clear: the animals blinked more when they saw humans doing the same. But the person’s identity also mattered. When facing their owner, the dogs’ blinking rate increased when the owner blinked. This difference did not appear in the same way with strangers.
One might then think that the dog immediately copies its human. Yet that is not what the measurements showed. The researchers checked whether a dog blinked within 1.5 seconds of the observed blink. No clear synchrony appeared, so this was not simply instant imitation, gesture after gesture.
Blinking primarily serves to protect and moisten the eye. The experiment nevertheless indicates that its frequency can also vary depending on what the other person does and on the relationship with that person. The dog therefore appears sensitive to a very subtle facial signal, even when speech, body movements and physical contact are absent.
This observation is consistent with previous research. Dogs had already been observed blinking more when watching videos of other dogs blinking. Other experiments had also found more blinking with their owner than with a familiar person. Here, using videos made it possible to isolate the eyelid movement and limit the other signals present during a real-life encounter.
It remains impossible, however, to assign a precise message to each blink. The study does not show that a dog deliberately closes its eyelids to “speak” to its owner. This behavior may instead accompany attention or social engagement.
The researchers now want to better understand how humans and dogs mutually modify their subtle gestures during genuine interactions.