Dogs can understand when humans mean well, even if they don’t get what they want from us. Prior to this work, the ability to distinguish between a human being unwilling or unable to perform a task had only been found in non-human primates.

The close social bond between humans and canines is well established, but researchers have a limited understanding of if and how dogs comprehend human intent. To see if pet dogs can distinguish between intentional and accidental actions by strangers, Christoph Völter at the University of Veterinary Medicine Vienna in Austria and his colleagues ran tests with humans offering dogs food while the animals’ body movements were tracked using eight cameras.

Each dog and human were separated by a transparent plastic panel with holes that a slice of sausage could be passed through. In 96 trials of 48 pet dogs, human participants either teased the dog by holding up and pulling back a treat, or they pretended to clumsily drop the piece of sausage on their own side of the panel before the dog could eat it.

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In all trials, the dogs had to wait 30 seconds before finally getting their reward, during which the team tracked their reaction. A machine learning algorithm trained to detect and follow specific points on the dogs’ bodies let the researchers analyse the dogs’ body language.

They found that when humans pretended to drop a treat compared with when they intentionally pulled it away, the dogs responded more patiently: they made more eye contact with the experimenter, wagged their tails more and stayed closer to the transparent barrier, suggesting they were still expecting a treat. Dogs that were teased sat, laid down and backed away the barrier more frequently. The results were similar across different dog breeds, ages and sex.

In the clumsy trial, the dogs also wagged their tails more on their right side, a behaviour known to be associated with dogs that are happy and relaxed. “They have more positive emotions towards the clumsy experimenter, which might indicate that they indeed understand that the experimenter is willing, but just too clumsy, to give them food,” says Völter.

Proceedings of the Royal Society B: Biological Sciences DOI: 10.1098/rspb.2022.1621