Editing Facial Action Coding System (section)

=== Cross-species applications ===
The original FACS has been modified to analyze facial movements in several non-human primates, namely [[Common chimpanzee|chimpanzee]]s,<ref name="pmid17352572">{{cite journal | vauthors = Parr LA, Waller BM, Vick SJ, Bard KA | title = Classifying chimpanzee facial expressions using muscle action | journal = Emotion | volume = 7 | issue = 1 | pages = 172–81 | date = February 2007 | pmid = 17352572 | pmc = 2826116 | doi = 10.1037/1528-3542.7.1.172 }}</ref> rhesus macaques,<ref>{{cite journal | vauthors = Parr LA, Waller BM, Burrows AM, Gothard KM, Vick SJ | title = Brief communication: MaqFACS: A muscle-based facial movement coding system for the rhesus macaque | journal = American Journal of Physical Anthropology | volume = 143 | issue = 4 | pages = 625–30 | date = December 2010 | pmid = 20872742 | pmc = 2988871 | doi = 10.1002/ajpa.21401 }}</ref> gibbons and siamangs,<ref>{{Cite journal | vauthors = Waller BM, Lembeck M, Kuchenbuch P, Burrows AM, Liebal K | title = GibbonFACS: A Muscle-Based Facial Movement Coding System for Hylobatids | doi = 10.1007/s10764-012-9611-6 | journal = International Journal of Primatology | volume = 33 | issue = 4 | pages = 809–821 | year = 2012 | s2cid = 18321096 }}</ref> and orangutans.<ref>{{Cite journal | vauthors = Caeiro CC, Waller BM, Zimmermann E, Burrows AM, Davila-Ross M | title = OrangFACS: A Muscle-Based Facial Movement Coding System for Orangutans (''Pongo'' spp.) | doi = 10.1007/s10764-012-9652-x | journal = International Journal of Primatology | volume = 34 | pages = 115–129 | year = 2012 | s2cid = 17612028 | url=http://irep.ntu.ac.uk/id/eprint/41473/1/1383920_Waller.pdf}}</ref> More recently, it was developed also for domestic species, including dogs,<ref>{{cite journal | vauthors = Waller BM, Peirce K, Caeiro CC, Scheider L, Burrows AM, McCune S, Kaminski J | title = Paedomorphic facial expressions give dogs a selective advantage | journal = PLOS ONE | volume = 8 | issue = 12 | pages = e82686 | year = 2013 | pmid = 24386109 | pmc = 3873274 | doi = 10.1371/journal.pone.0082686 | bibcode = 2013PLoSO...882686W | doi-access = free }}</ref> horses<ref>{{cite journal | vauthors = Wathan J, Burrows AM, Waller BM, McComb K | title = EquiFACS: The Equine Facial Action Coding System | journal = PLOS ONE | volume = 10 | issue = 8 | pages = e0131738 | date = 2015-08-05 | pmid = 26244573 | pmc = 4526551 | doi = 10.1371/journal.pone.0131738 | bibcode = 2015PLoSO..1031738W | doi-access = free }}</ref> and cats.<ref>{{Cite journal| vauthors = Caeiro CC, Burrows AM, Waller BM |date=2017-04-01|title=Development and application of CatFACS: Are human cat adopters influenced by cat facial expressions?|journal=Applied Animal Behaviour Science|volume=189|pages=66–78|doi=10.1016/j.applanim.2017.01.005|issn=0168-1591|url=http://eprints.lincoln.ac.uk/25940/1/25940%20Proof_APPLAN_4392.pdf}}</ref> Similarly to the human FACS, the animal FACS has manuals available online for each species with the respective certification tests.<ref>{{Cite web|url=http://animalfacs.com|title=Home|website=animalfacs.com|access-date=2019-10-23}}</ref>

Thus, the FACS can be used to compare facial repertoires across species due to its anatomical basis. A study conducted by Vick and others (2006) suggests that the FACS can be modified by taking differences in underlying morphology into account. Such considerations enable a comparison of the homologous facial movements present in humans and chimpanzees, to show that the facial expressions of both species result from extremely notable appearance changes. The development of FACS tools for different species allows the objective and anatomical study of facial expressions in communicative and emotional contexts. Furthermore, a cross-species analysis of facial expressions can help to answer interesting questions, such as which emotions are uniquely human.<ref>{{cite journal | vauthors = Vick SJ, Waller BM, Parr LA, Smith Pasqualini MC, Bard KA | title = A Cross-species Comparison of Facial Morphology and Movement in Humans and Chimpanzees Using the Facial Action Coding System (FACS) | journal = Journal of Nonverbal Behavior | volume = 31 | issue = 1 | pages = 1–20 | date = March 2007 | pmid = 21188285 | pmc = 3008553 | doi = 10.1007/s10919-006-0017-z }}</ref>

The  Emotional Facial Action Coding System (EMFACS)<ref>{{citation | vauthors = Friesen W, Ekman P | title = EMFACS-7: Emotional Facial Action Coding System. Unpublished manuscript | publisher = University of California at San Francisco | date = 1983 | volume = 2 | issue = 36 | pages = 1 }}</ref> and the  Facial Action Coding System Affect Interpretation Dictionary (FACSAID)<ref>{{Cite web |url=http://www.face-and-emotion.com/dataface/facsaid/description.jsp |title=Facial Action Coding System Affect Interpretation Dictionary (FACSAID) |access-date=2011-02-23 |archive-url=https://web.archive.org/web/20110520164308/http://face-and-emotion.com/dataface/facsaid/description.jsp |archive-date=2011-05-20 |url-status=dead }}</ref> consider only emotion-related facial actions. Examples of these are:
{| class="wikitable sortable"
|-
! Emotion !! Action units
|-
| Happiness ||6+12
|-
| Sadness || 1+4+15
|-
| Surprise ||  1+2+5B+26
|-
| Fear || 1+2+4+5+7+20+26
|-
| Anger || 4+5+7+23
|-
| Disgust || 9+15+17
|-
| Contempt || R12A+R14A
|}