Editing Facial Action Coding System (section)

{{Short description|System of classifying human facial movements}}
[[File:1106 Side Views of the Muscles of Facial Expressions.jpg|thumb|upright=1.3|Muscles of head and neck]]

The '''Facial Action Coding System''' ('''FACS''') is a system to [[taxonomize]] human [[facial expression|facial movements]] by their appearance on the face,  based on a system originally developed by a Swedish [[anatomist]] named [[Carl-Herman Hjortsjö]].<ref>{{cite book|url=https://books.google.com/books?id=BakQAQAAIAAJ|vauthors=Hjortsjö CH|title=Man's face and mimic language|year=1969}} free download: [http://diglib.uibk.ac.at/ulbtirol/content/titleinfo/782346 Carl-Herman Hjortsjö, Man's face and mimic language"] {{Webarchive|url=https://web.archive.org/web/20220806115847/https://diglib.uibk.ac.at/ulbtirol/content/titleinfo/782346 |date=2022-08-06 }}</ref> It was later adopted by [[Paul Ekman]] and [[Wallace V. Friesen]], and published in 1978.<ref>{{cite book | vauthors = Ekman P, Friesen W | title = Facial Action Coding System: A Technique for the Measurement of Facial Movement. | publisher = Consulting Psychologists Press | location = Palo Alto | date = 1978 }}</ref> Ekman, Friesen, and Joseph C. Hager published a significant update to FACS in 2002.<ref>{{cite book | first1 = Paul | last1 = Ekman | first2 = Wallace V. | last2 = Friesen | first3 = Joseph C. | last3 = Hager | name-list-style = vanc | title = Facial Action Coding System: The Manual on CD ROM. | publisher = A Human Face | location = Salt Lake City | date = 2002 }}</ref> Movements of individual [[facial muscles]] are encoded by the FACS from slight different instant changes in facial appearance. It has proven useful to [[psychologist]]s and to [[animator]]s.