Dogs give their “puppy-dog eyes” look when humans are looking at them but are unlikely to alter their facial expressions for food, according to new research.
Scientists at the University of Portsmouth’s Dog Cognition Centre say they are the first to find clear evidence that dogs move their faces in direct response to human attention.
A spokeswoman said: “Dogs don’t respond with more facial expressions upon seeing tasty food, suggesting that dogs produce facial expressions to communicate and not just because they are excited.
“Brow-raising, which makes the eyes look bigger — so-called puppy-dog eyes — was the dogs’ most commonly used expression in this research.”
Dr Juliane Kaminski, who led the study published in Scientific Reports, said: "We can now be confident that the production of facial expressions made by dogs are dependent on the attention state of their audience and are not just a result of dogs being excited. In our study they produced far more expressions when someone was watching, but seeing food treats did not have the same effect.
“The findings appear to support evidence dogs are sensitive to humans’ attention and that expressions are potentially active attempts to communicate, not simple emotional displays.”
Dr Kaminski said that previously it was thought that animal expressions were involuntary and dependent on the individual’s emotional state, rather than being a response to their audience.
She suggested that dogs’ facial expressions might have changed as part of the process of becoming domesticated.
The researchers studied 24 family pet dogs of various breeds, aged one to 12.
Each dog was tied by a lead a metre away from a person, and the dogs’ faces were filmed throughout a range of exchanges, from the person being oriented towards the dog, to being distracted and with their body turned away from the dog.
The dogs’ facial expressions were measured using DogFACS, an anatomically-based coding system which gives a reliable and standardised measurement of facial changes linked to underlying muscle movement.