If you know when your dog is sad or happy, the credit goes to your experience and learning, not an innate ability to read the facial expression of your "best friend", suggests new research.
While some dog emotions can be recognised from early on, the ability to reliably recognise dog emotions is mainly acquired through age and experience, said the study.
The findings, published in the journal Scientific Reports, showed that the probability of recognising dog emotions was higher for participants who grew up in a cultural context with a positive attitude towards dogs, regardless of whether they owned a dog themselves.
"These results are noteworthy, because they suggest that it is not necessarily direct experience with dogs that affects humans' ability to recognise their emotions, but rather the cultural milieu in which humans develop," said study lead author Federica Amici from the Max Planck Institute in Germany.
In order to test how well humans can understand the emotions behind dog facial expressions, the researchers collected photographs of dogs, chimpanzees, and humans displaying either happy, sad, angry, neutral, or fearful emotions as substantiated by the photographers.
They then recruited 89 adult participants and 77 child participants and categorised them according to their age, the dog-positivity of their cultural context and the participants' personal history of dog ownership.
Each participant was presented with photographs of dogs, chimps and humans and asked to rate how much the individual in the picture displayed happiness, sadness, anger, or fear.
Adults were also asked to determine the context in which the picture had been taken (e.g., playing with a trusted conspecific partner; directly before attacking a conspecific).
The results of the study showed that, while some dog emotions can be recognised from early on, the ability to reliably recognise dog emotions is mainly acquired through age and experience.
In adults, the probability of recognising dog emotions was higher for participants who grew up in a cultural context with a positive attitude towards dogs, regardless of whether they owned a dog themselves.
A dog-positive cultural background, one in which dogs are closely integrated into human life and considered highly important, may result in a higher level of passive exposure and increased inclination and interest in dogs, making humans better at recognising dogs' emotions even without a history of personal dog ownership.
The researchers also found that regardless of age or experience with dogs, all participants were able to identify anger and happiness reliably.
While these results may suggest an innate ability favoured by the co-domestication hypothesis, it is also possible that humans learn to recognise these emotions quickly, even with limited exposure.
Other than anger and happiness,the children in the study were not good at identifying dog emotions, the study said.