Facial Action Coding System

Muscles of head and neck.

Facial Action Coding System (FACS) is a system to taxonomize human facial movements by their appearance on the face, based on a system originally developed by a Swedish anatomist named Carl-Herman Hjortsjö.[1] It was later adopted by Paul Ekman and Wallace V. Friesen, and published in 1978.[2] Ekman, Friesen, and Joseph C. Hager published a significant update to FACS in 2002.[3] Movements of individual facial muscles are encoded by FACS from slight different instant changes in facial appearance.[4] It is a common standard to systematically categorize the physical expression of emotions, and it has proven useful to psychologists and to animators. Due to subjectivity and time consumption issues, FACS has been established as a computed automated system that detects faces in videos, extracts the geometrical features of the faces, and then produces temporal profiles of each facial movement.[4]

Uses

Using FACS,[5] human coders can manually code nearly any anatomically possible facial expression, deconstructing it into the specific Action Units (AU) and their temporal segments that produced the expression. As AUs are independent of any interpretation, they can be used for any higher order decision making process including recognition of basic emotions, or pre-programmed commands for an ambient intelligent environment. The FACS Manual is over 500 pages in length and provides the AUs, as well as Ekman's interpretation of their meaning.

FACS defines AUs, which are a contraction or relaxation of one or more muscles. It also defines a number of Action Descriptors, which differ from AUs in that the authors of FACS have not specified the muscular basis for the action and have not distinguished specific behaviors as precisely as they have for the AUs.

For example, FACS can be used to distinguish two types of smiles as follows:[6]

Although the labeling of expressions currently requires trained experts, researchers have had some success in using computers to automatically identify FACS codes, and thus quickly identify emotions.[7] Computer graphical face models, such as CANDIDE or Artnatomy, allow expressions to be artificially posed by setting the desired action units.

The use of FACS has been proposed for use in the analysis of depression,[8] and the measurement of pain in patients unable to express themselves verbally.[9]

FACS is designed to be self-instructional. People can learn the technique from a number of sources including manuals and workshops,[10] and obtain certification through testing.[11] The original FACS has been modified to analyze facial movements in several non-human primates, namely chimpanzees,[12] rhesus macaques,[13] gibbons and siamangs,[14] and orangutans.[15] More recently, it was adapted for a domestic species, the dog.[16]

Thus, 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 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.[17]

EMFACS (Emotional Facial Action Coding System)[18] and FACSAID (Facial Action Coding System Affect Interpretation Dictionary)[19] consider only emotion-related facial actions. Examples of these are:

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+16
Contempt R12A+R14A

Codes for Action Units

For clarification, FACS is an index of facial expressions, but does not actually provide any bio-mechanical information about the degree of muscle activation. Though muscle activation is not part of FACS, the main muscles involved in the facial expression have been added here for the benefit of the reader.

Action Units (AUs) are the fundamental actions of individual muscles or groups of muscles.

Action Descriptors (ADs) are unitary movements that may involve the actions of several muscle groups (e.g., a forward‐thrusting movement of the jaw). The muscular basis for these actions hasn't been specified and specific behaviors haven't been distinguished as precisely as for the AUs.

For most accurate annotation, FACS suggests agreement from at least two independent certified FACS encoders.

Intensity Scoring

Intensities of FACS are annotated by appending letters A–E (for minimal-maximal intensity) to the Action Unit number (e.g. AU 1A is the weakest trace of AU 1 and AU 1E is the maximum intensity possible for the individual person).

List of Action Units and Action Descriptors (with underlying facial muscles)

Main Codes

AU Number FACS Name Muscular Basis
0 Neutral face
1 Inner Brow Raiser frontalis (pars medialis)
2 Outer Brow Raiser frontalis (pars lateralis)
4 Brow Lowerer depressor glabellae, depressor supercilii, corrugator supercilii
5 Upper Lid Raiser levator palpebrae superioris, superior tarsal muscle
6 Cheek Raiser orbicularis oculi (pars orbitalis)
7 Lid Tightener orbicularis oculi (pars palpebralis)
8 Lips Toward Each Other orbicularis oris
9 Nose Wrinkler levator labii superioris alaeque nasi
10 Upper Lip Raiser levator labii superioris, caput infraorbitalis
11 Nasolabial Deepener zygomaticus minor
12 Lip Corner Puller zygomaticus major
13 Sharp Lip Puller levator anguli oris (also known as caninus)
14 Dimpler buccinator
15 Lip Corner Depressor depressor anguli oris (also known as triangularis)
16 Lower Lip Depressor depressor labii inferioris
17 Chin Raiser mentalis
18 Lip Pucker incisivii labii superioris and incisivii labii inferioris
19 Tongue Show
20 Lip Stretcher risorius w/ platysma
21 Neck Tightener platysma
22 Lip Funneler orbicularis oris
23 Lip Tightener orbicularis oris
24 Lip Pressor orbicularis oris
25 Lips Part depressor labii inferioris, or relaxation of mentalis or orbicularis oris
26 Jaw Drop masseter; relaxed temporalis and internal pterygoid
27 Mouth Stretch pterygoids, digastric
28 Lip Suck orbicularis oris
29 Jaw Thrust
30 Jaw Sideways
31 Jaw Clencher masseter
32 [Lip] Bite
33 [Cheek] Blow
34 [Cheek] Puff
35 [Cheek] Suck
36 [Tongue] Bulge
37 Lip Wipe
38 Nostril Dilator nasalis (pars alaris)
39 Nostril Compressor nasalis (pars transversa) and depressor septi nasi
41 Glabella Lowerer Separate Strand of AU 4: depressor glabellae (aka procerus)
42 Inner Eyebrow Lowerer Separate Strand of AU 4: depressor supercilii
43 Eyes Closed Relaxation of levator palpebrae superioris
44 Eyebrow Gatherer Separate Strand of AU 4: corrugator supercilii
45 Blink Relaxation of levator palpebrae superioris; contraction of orbicularis oculi (pars palpebralis)
46 Wink orbicularis oculi

Head Movement Codes

AU Number FACS Name Action
51 Head Turn Left
52 Head Turn Right
53 Head Up
54 Head Down
55 Head Tilt Left
M55 Head Tilt Left The onset of the symmetrical 14 is immediately preceded or accompanied by a head tilt to the left.
56 Head Tilt Right
M56 Head Tilt Right The onset of the symmetrical 14 is immediately preceded or accompanied by a head tilt to the right.
57 Head Forward
M57 Head Thrust Forward The onset of 17+24 is immediately preceded, accompanied, or followed by a head thrust forward.
58 Head Back
M59 Head Shake Up and Down The onset of 17+24 is immediately preceded, accompanied, or followed by an up-down head shake (nod).
M60 Head Shake Side to Side The onset of 17+24 is immediately preceded, accompanied, or followed by a side to side head shake.
M83 Head Upward and to the Side The onset of the symmetrical 14 is immediately preceded or accompanied by a movement of the head, upward and turned and/or tilted to either the left or right.

Eye Movement Codes

AU Number FACS Name Action
61 Eyes Turn Left
M61 Eyes Left The onset of the symmetrical 14 is immediately preceded or accompanied by eye movement to the left.
62 Eyes Turn Right
M62 Eyes Right The onset of the symmetrical 14 is immediately preceded or accompanied by eye movement to the right.
63 Eyes Up
64 Eyes Down
65 Walleye
66 Cross-eye
M68 Upward Rolling of Eyes The onset of the symmetrical 14 is immediately preceded or accompanied by an upward rolling of the eyes.
69 Eyes Positioned to Look at Other Person The 4, 5, or 7, alone or in combination, occurs while the eye position is fixed on the other person in the conversation.
M69 Head and/or Eyes Look at Other Person The onset of the symmetrical 14 or AUs 4, 5, and 7, alone or in combination, is immediately preceded or accompanied by a movement of the eyes or of the head and eyes to look at the other person in the conversation.

Visibility Codes

AU Number FACS Name
70 Brows and forehead not visible
71 Eyes not visible
72 Lower face not visible
73 Entire face not visible
74 Unscorable

Gross Behavior Codes

These codes are reserved for recording information about gross behaviors that may be relevant to the facial actions that are scored.

AU Number FACS Name
40 Sniff
50 Speech
80 Swallow
81 Chewing
82 Shoulder shrug
84 Head shake back and forth
85 Head nod up and down
91 Flash
92 Partial flash
97* Shiver/Tremble
98* Fast up-down look

See also

References

  1. ↑ Hjorztsjö, CH (1969). Man's face and mimic language. free download: Carl-Herman Hjortsjö, Man's face and mimic language"
  2. ↑ P. Ekman and W. Friesen. Facial Action Coding System: A Technique for the Measurement of Facial Movement. Consulting Psychologists Press, Palo Alto, 1978.
  3. ↑ Paul Ekman, Wallace V. Friesen, and Joseph C. Hager. Facial Action Coding System: The Manual on CD ROM. A Human Face, Salt Lake City, 2002.
  4. 1 2 Hamm, J.; Kohler, C. G.; Gur, R. C.; Verma, R. (2011). "Automated Facial Action Coding System for dynamic analysis of facial expressions in neuropsychiatric disorders". Journal of Neuroscience Methods. 200 (2): 237–256. doi:10.1016/j.jneumeth.2011.06.023. PMC 3402717Freely accessible. PMID 21741407.
  5. ↑ Freitas-Magalhães, A. (2012). Microexpression and macroexpression. In V. S. Ramachandran (Ed.), Encyclopedia of Human Behavior (Vol. 2, pp. 173–183). Oxford: Elsevier/Academic Press. ISBN 978-0-12-375000-6
  6. ↑ Del Giudice, M.; Colle, L. (2007). "Differences between children and adults in the recognition of enjoyment smiles". Developmental Psychology. 43 (3): 796–803. doi:10.1037/0012-1649.43.3.796. PMID 17484588.
  7. ↑ Facial Action Coding System. Retrieved July 21, 2007.
  8. ↑ Reed, L. I.; Sayette, M. A.; Cohn, J. F. (2007). "Impact of depression on response to comedy: A dynamic facial coding analysis". Journal of Abnormal Psychology. 116 (4): 804–809. doi:10.1037/0021-843X.116.4.804. PMID 18020726.
  9. ↑ Lints-Martindale, A. C.; Hadjistavropoulos, T.; Barber, B.; Gibson, S. J. (2007). "A Psychophysical Investigation of the Facial Action Coding System as an Index of Pain Variability among Older Adults with and without Alzheimer's Disease". Pain Medicine. 8 (8): 678–689. doi:10.1111/j.1526-4637.2007.00358.x. PMID 18028046.
  10. ↑ Example and web site of one teaching professional: Erika L. Rosenberg, Ph.D
  11. ↑ Archived December 23, 2008, at the Wayback Machine.
  12. ↑ Parr, L. A.; Waller, B. M.; Vick, S. J.; Bard, K. A. (2007). "Classifying chimpanzee facial expressions using muscle action". Emotion. 7 (1): 172–181. doi:10.1037/1528-3542.7.1.172. PMC 2826116Freely accessible. PMID 17352572.
  13. ↑ Parr, L. A.; Waller, B. M.; Burrows, A. M.; Gothard, K. M.; Vick, S. J. (2010). "Brief communication: MaqFACS: A muscle-based facial movement coding system for the rhesus macaque". American Journal of Physical Anthropology. 143 (4): 625–630. doi:10.1002/ajpa.21401. PMC 2988871Freely accessible. PMID 20872742.
  14. ↑ Waller, B. M.; Lembeck, M.; Kuchenbuch, P.; Burrows, A. M.; Liebal, K. (2012). "GibbonFACS: A Muscle-Based Facial Movement Coding System for Hylobatids". International Journal of Primatology. 33 (4): 809. doi:10.1007/s10764-012-9611-6.
  15. ↑ Caeiro, C. T. C.; Waller, B. M.; Zimmermann, E.; Burrows, A. M.; Davila-Ross, M. (2012). "OrangFACS: A Muscle-Based Facial Movement Coding System for Orangutans (Pongo spp.)". International Journal of Primatology. 34: 115. doi:10.1007/s10764-012-9652-x.
  16. ↑ Waller, B. M.; Peirce, K.; Caeiro, C. C.; Scheider, L.; Burrows, A. M.; McCune, S.; Kaminski, J. (2013). "Paedomorphic Facial Expressions Give Dogs a Selective Advantage". PLoS ONE. 8 (12): e82686. doi:10.1371/journal.pone.0082686. PMC 3873274Freely accessible. PMID 24386109.
  17. ↑ Vick, S. J.; Waller, B. M.; Parr, L. A.; Smith Pasqualini, M. C.; Bard, K. A. (2006). "A Cross-species Comparison of Facial Morphology and Movement in Humans and Chimpanzees Using the Facial Action Coding System (FACS)". Journal of Nonverbal Behavior. 31 (1): 1–20. doi:10.1007/s10919-006-0017-z. PMC 3008553Freely accessible. PMID 21188285.
  18. ↑ Friesen, W.; Ekman, P. (1983). EMFACS-7: Emotional Facial Action Coding System. Unpublished manual, University of California, California.
  19. ↑ Facial Action Coding System Affect Interpretation Dictionary (FACSAID)

External links

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