Emotions are instant and they often show. I would say that the face is where you should look for these, emotions.
I read somewhere about mirror neurons, that they grant us the possibilty to immedietly take in the emotion of another human being. My mirror neurons are reflecting your emotion and I feel what you feel without having tho go through the intellectual reading of it. That comes later and is called “dealing with it”.
When working with emotions from a physical point of view, it becomes clear that emotions does not last for long. Some emotions come easier, some is really hard to bring out. It might depend on your daily condition, it might relate to whether the emotion is easily handled or not. Maybe, one does not freely bring out sorrow if it is an emotion that you tried to escape for a while.
So emotions, like fluctuant materia, cannot be kept for a long time; they have to become something else.
We start with the emotion, we let it travel into the face and when the emotion is gone- the face remains. The face keeps moving. This movement can go anywhere, become anything.
Emotions change, so does movement.