Robert J Sternberg. 2004 Thomson Wadsworth.
The physical appearance of emotions
As it is important to communicate visually, it is essential to find a common denominator that everyone can relate to. The similarity of facial expressions used across cultures can be used as a universal language. People are experts in facial expression and read people in this manner, everyday. By focusing on a humans emotions and catching this in their facial movements, you can convey a sense of universal understanding on how the individual is feeling.
A study was undertaken to identify facial expressions between various, contrasting cultures. New Guineans were participants and though they have barely any interactions wuith Western culture, their facial expressions were very similar to those in the United States. (Page 456/7 Figure 12.6 Cultural agreement regarding facial expressions. From Unmasking the Face. 2nd Edition, by Ekman & Frisen. Copyright 1984)
This would be good when shooting for film, by shooting close ups of the facial features moving it can create a sense of emotion and through no need for dialect, everyone understands the given situation and can read the emotions.