Detecting Happiness Using Hyperspectral Imaging Technology

Table 2

Association between ROIs, muscle groups, AUs, and related studies.

Symbol^a	Quantity	Principal muscle groups	Associated AU of smile	ROI-related studies
L1, R1	Upper eyelid	Orbicularis oculi	AU6	Matzke et al. [46], Forte et al. [47]
L2, R2	Eye corner around temple	Temporalis	AU6	Ekman [42], Knoll et al. [48]
L3, R3	Eye corner around ophryon	Orbicularis oculi	AU6	Rajoub and Zwiggelaar [49], Pavlidis et al. [50]
L4, R4	Cheek	Zygomaticus	AU6, AU10, AU12	Kim and Provost [45], Kohler et al. [51]
L5, R5	Lower eyelid	Orbicularis oculi	AU6	Knoll et al. [48], Kashima et al. [52]
L6, R6	Oculonasal groove	Levator labii superioris	AU10	Matzke et al. [46], Whitton et al. [53]
L7, R7	Angulus oris	Composites of buccinator, masseter or risorius	AU12, AU20, AU25	Fischer et al. [44]
M1	Forehead	Frontalis		Kim and Provost [45], Chen et al. [30]
M2	Ophryon	Procerus		Finzi and Rosenthal [54], Vitti and Basmajian [55]
M3	Nose	Nasalis		Fischer et al. [44]
M4	Perinasal	Orbicularis oris	AU25	Pavlidis et al. [24]
M5	Mandible	Mentalis	AU25	Harrison et al. [56]

^aL = left; R = right; M = middle.