Engagement detection in online learning: a review

Smart Learning Environments

Table 1 List of AUs involved in engagement detection using facial expressions in online learning

Engagement Levels	Action Units	Methods
Boredom	AU4, AU7, AU12	McDaniel et al. (2007)
Confusion	AU1, AU4, AU7, AU12
Delight	AU4, AU7, AU12, AU25, AU26
Frustration	AU12
Neutral	AU4, AU7, AU12, AU25, AU26
Difficulties in viewing speed	AU1, AU2, AU4, AU5, AU9, AU10, AU12, AU14, AU15, AU17, AU20, AU45	Whitehill et al. (2008, 2014)
Confusion	AU4, AU7	Grafsgaard et al. (2013a, 2013b)
Frustration	AU1, AU2, AU4
Learning Gain	AU2, AU14
Confusion	AU45, AU1, AU4	Bosch (2016); Bosch et al. (2014, 2015, 2016)
Frustration	AU45, head pose feature	Bosch (2016); Bosch et al. (2014, 2015, 2016)
Learning Gain	AU2, AU4, AU5, AU12, AU15, AU23	Vail et al. (2016a); Vail et al. (2016b)