Dogs know if that’s a smile or a frown

Sympathetic head tilts, excited tails or a cold shoulder are all responses from dogs suggesting they can sense our expressions. Research this week in Current biology by Corsin Müller and his team from the University of Veterinary Medicine in Vienna, has provided evidence that dogs can distinguish between happy and angry faces.

The research was carried out on 11 dogs which were trained to recognise happy or angry faces when they were only shown either the upper or lower half of a human face. The testing stage of the trial then involved showing the dog either the other half of the face used in training, the same half as that used in training but of a different person or the whole left side of the face used in training.

The results showed that the dogs were able to distinguish between happy and angry faces more times than would be expected by chance, suggesting the dogs could transfer what they learned in the first stage. Müller explained that the dogs are likely to likely “associate a smiling face with a positive meaning and an angry facial expression with a negative meaning.” He suggested that ‘life-long co-habitation’ with humans provides high exposure to human facial expressions, giving them many opportunities to learn.

The question now is whether dogs with less exposure to people are less effective at distinguishing expressions. Research is currently being planned in other species such as cats and pigs to examine the role of domestication in the ability to read human expressions, and further research is planned to study how dogs express different emotions, and how their feelings are influenced by humans.