*2.4. Emotion and Learning*

The research carried out in education and psychology shows that emotion and learning have a hidden correlation, which will ultimately enhance learning performance [26]. Russell (1980) has built a 2D emotion model diagram and the eight emotions are divided into four quadrants, namely, happiness, surprise, boredom, fear, calmness, sadness, disgust and anger [27]. Ekman and Friesen (1971) defined six facial expressions: happiness, anger, fear, disgust, surprise and sadness [28]. Because emotions may affect learning effectiveness and the learning process may also influence the emotions, the correlation has therefore led many studies to focus on emotions and teaching. As Guo Shuzhen pointed out (2010), tutors need to be able to guide students to think in a right direction, influence students in a practical way, cultivate positive thinking and problem-solving ability, trigger students' potential abilities and improve learning effects in a happy learning way [29]. As Wen-Tzu Chiang (2004) proposed, the best way to adjust your emotion is to shift your attention away from your current mood and change the way you think and the point of view with which you view things [30]. Ying-Chun Sun (2009) pointed out that the cognitive style can generate different learning effects for understanding different emotions during the learning process. Therefore, in order to improve learning motivation, students shall be guided to maintain positive thinking over time to achieve optimal effect of learning [31].

### *2.5. Eye Movement Analysis*

In recent years, eye tracking has been widely used as a research tool in many fields [32,33]. By tracking the user's fixation and analyzing eye movements and pupil size, his/her cognitive state can be studied, such as attention pattern and learning preferences [34,35]. Eye movement analysis mainly seeks to detect the learner's distraction process and understand the learner's attention on news reading through fixation points and eye movement trajectories [36]. As for eye movements upon reading, as Rayner (2009) said, tracking eye movements is regarded as an intuitive and effective approach to explore people's cognitive process in reading, scene perception and visual search [37]. The average fixation duration is 260–330 ms when the reader

views images and 225–250 ms when reading words. The movement of fixation is to follow the texts from left to right or up to down. About 10–15% of fixation is associated with looking back, moving in an opposite direction of the text order. The situation is due to the fact that the reader spends a longer time reading the text and has to look back. If more than ten words are looked back by the reader, it indicates that the reader does not understand the current texts. Attention is a very important step for learning education because you shall first attract the attentions of learners before starting to tutor knowledge [38]. Many researchers agree that the direction of the head in interpersonal interaction is the easiest way to know the direction of the individual's fixation. When the head is fixed, the eye direction is almost the same as that of the individual's attention, except when the subject suffers from severe strabismus [39]. When the head is fixed, the eye direction is the same as that of the individual's fixation [36].
