Table 1.
Comparison of facial movements (Action Units) in humans, chimpanzees and macaques.
| Action Unit | Action Descriptor Name | Muscle (see Fig 1) | Human | Chimpanzee | Macaque | AU In MaqFACS? |
|---|---|---|---|---|---|---|
| AU1 | inner brow raiser | medial frontalis | Y* | NO* | NO* | no |
| AU2 | outer brow raiser | lateral frontalis | Y* | NO* | NO* | no |
| AU1+2 | brow raiser | frontalis | Y* | Y* | Y* | yes |
| AU4 | brow lowerer | 1CS, 2DS, 3Proc | Y* | NO*3 | NO*1,3 | no |
| AU41 | glabella lowerer | procerus | Y* | NO* | Y* | yes |
| AU5 | upper lid raiser | orb. oculi | Y^ | NO^ | NO^ | no |
| AU6 | cheek raiser | orb. oculi (orbital) | Y* | Y* | Y* | yes |
| AU7 | lid tightener | orb. oculi (palpebral) | Y^ | Y^ | Y^ | no |
| AU8 | lips towards each other | orb. oris | Y^ | NO^ | Y^ | yes |
| AU9 | nose wrinkle | llsan | Y* | Y* | Y* | yes |
| AU10 | upper lip raiser | lev. labii sup | Y^ | Y* | Y* | yes |
| AU11 | nasiolabial furrow deepener | zyg. minor | Y | NO | NO^ | no |
| AU12 | lip corner puller | zyg. major | Y* | Y* | Y* | yes |
| AU13 | cheek puffer | caninus4 | Y* | NO | NO | no |
| AU14 | dimpler | buccinator | Y | NO^ | NO^ | no |
| AU15 | lip corner depressor | dep. anguli oris6 | Y* | NO* | NO* | no |
| AU16 | lower lip depressor | depressorlabii inf | Y* | Y* | Y* | yes |
| AU17 | chin raiser | mentalis | Y* | Y* | Y* | yes |
| AU18 | lip pucker | orb. oris | Y^ | NO | Y* | yes5 |
| AU20 | lip stretcher | risorius | Y* | NO | NA | no |
| AU22 | lip funneler | orb. oris | Y^ | Y* | NO | no |
| AU25 | lips parted | various | Y^ | Y^ | Y^ | yes |
| AU26 | jaw drop | various | Y^ | Y^ | Y^ | yes |
| AU27 | mouth stretch | various | Y^ | Y^ | Y^ | yes |
| AU28 | lip suck | orb. oris | Y^ | Y^ | NO^ | no |
| EAU1 | ears forward | ant. auricularis | NO^ | NO^ | Y* | yes |
| EAU2 | ear elevator | sup. auricularis | NO^ | NO^ | Y* | yes |
| EAU3 | ear flattener | post. auricularis | NO^ | NO^ | Y* | yes |
4
The caninus is also referred to as the levator anguli oris in humans
5
In macaques, we have divided AU18 into two separate AU codes, AU18i-true pucker and AU18ii-outer pucker (see text)
6
Also referred to as triangularis
Observed movements are noted with ‘Y’ and those not observed are noted with ‘NO.’ Independent stimulation of these movements is marked by an asterisk (*) for humans and chimpanzees (Waller et al., 2006) and macaques (Waller et al., 2008). If no stimulation was attempted, these are marked by a carrot (^). No * or ^ listed means that stimulation was attempted but was not successful. If the muscle was not present on dissection, ‘NA’ is noted.