I have had dogs all my life, and they do learn to associate facial expressions with emotions, like wise they come to recognize tones of voice.
They have and amazing sense of time and routine expecting certain actions at certain times.
They are pack animals and once the family alpha is imprinted on them, they will emulate him or her, even at times trying to emulate pack language, laughter, verbal snapping, simple words like yes and no etc, like wise subconsciously humans also pick up dog body language and sounds, clicking the tongue, huffing a greeting, tilting the head to the left to indicated paying attention even growling.
It is even more pronounced with cats who are sly little buggers that will manipulate humans without their even knowing.