Using long exposure we could visually represent how human emotion looks in an abstract way. In a well lite studio with a black background we could use a golden light which would move around a person in the shot. Depending on the emotion we are trying to convey will move the light in a appropriate manner.
So if the person is feeling angry the light will move in a sharp and erratic way. If their sad that it could be slow and smooth etc.
This technique I think can work really well to pull off an attractive piece of motion that has a deep meaning while still being abstract.