Dogs can discern different facial expressions and actually study faces much as we do, according to research published in Plos One.* Scientists used gaze-tracking technology to determine that dogs focus first on the eyes before considering the mid-face and then the mouth. Humans and other primates read faces in a similar fashion.
In the study, 31 dogs from 13 different breeds were presented with digital colour photos of unfamiliar human and canine faces that demonstrated either threatening, pleasant or neutral expressions. Overall, the dogs avoided photos of angry humans, looking quickly away from the images. They stared longest at photos of dogs with threatening expressions.
*Somppi S, Törnqvist H, Kujala MV, Hänninen L, Krause CM, Vainio O. (2016) “Dogs Evaluate Threatening Facial Expressions by Their Biological Validity — Evidence from Gazing Patterns”. PLoS ONE 11(1): e0143047. doi:10.1371/journal.pone.0143047.