The dogs completed two trials on separate days.
The researchers found the dogs were more expressive when the lead was facing them and paying attention, but whether or not he or she had food made little to no difference.
The dogs also barked more and stuck their tongues out when they received attention.
"This simply shows that dogs produce more (but not different) facial movements when someone is looking at them," lead researcher Juliane Kaminski told the New York Times.
According to the Dog Cognition Centre’s Bridget Waller, who designed a dog version of the human Facial Action Coding System, those puppy dog eyes or the “inner brow raiser” expression in humans may indicate sadness in people, but there’s no evidence for the same in dogs.
Additionally, Kaminski actually warns against speculating why dogs use the look or that they use specific expressions to communicate a specific message at all.
“This kind of ‘dinner table effect’ that dogs try and look super cute when they want something is something we did in fact not find,” she wrote. “Dogs do not seem to produce facial movement as a kind of reflex to being aroused,” Kaminski wrote.
In fact, Fido’s expression may just be a reflection of your own.
The study should serve as a reminder that people respond involuntarily to their pets’ actions, Brian Hare, professor at Duke University and director of the school’s canine cognition center, told the New York Times.
Hare, who was not invovled in the study, added that when we interact with our dogs, physicial features and eye contact influence how we feel about them.
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“It really mirrors how our interactions occur with our own species,” Hare said, and said this kind of information may be useful for screening potential service dogs and during a puppy adoption process.
Emory University researcher Gregory Berns, who has used brain scans to explore dog behavior, told the journal “Nature” that future research could look into whether dogs use specific expressions, such as the puppy dog eyes look, based on the identity of the person they’re with.
Read more at Nature.com.