Psychology Today has a fascinating artilce on the study of dogs and their reaction to human faces
"Research shows that dogs pay particularly close attention to human facial expressions—perhaps because we don’t have tails and our ears don’t move."
Psychology Today has a fascinating article about just how good dogs are at reading human facial experessions, as well as their responses. Dogs turn to mouth-licking as a way to respond to their perception of our 'angry face.'
Apparently, just like humans, dogs release oxytocin. They do this when seeing a happy, human face. This is the 'trust hormone,' which builds bonds in humans … and in dogs!
They even used fMRI (functional Magnetic Resonance Imaging) to study dog brains while showing the dogs human faces. This is non-invasive and harmless to the dogs.