FACS is a much more mathematic and systematic approach to coding facial expressions. While Annie is FACS certified, she doesn’t use FACS coding in her work. Her methods are based on her experience living in 9 countries and studying 8 languages over a period of 25 years. If you are interested in FACS specifically, Annie recommends the work of Paul Ekman, Wallace Friesen, and Erika Rosenberg.