Facial recognition technology was introduced in the 1960s, languished through the AI winter, and in recent years has taken off -- boosted by increasingly powerful deep neural networks. Facial recognition has been applied in Face ID device unlocking functions, public security services, smart payment systems and more. During Taylor Swift's 2018 "Reputation" tour, the American singer-songwriter's security team utilized the tech to safeguard her from stalkers. Now, a research team from the Hong Kong University of Science and Technology and Harbin Engineering University has adopted facial recognition technology to analyze students' emotions in the classroom through a visual analytics system called "EmotionCues." Paper co-author Huamin Qu says the system "provides teachers with a quick and convenient measure of students' engagement level in a class. Knowing whether the lectures are too hard and when students get bored can help improve teaching."