Does an instructor's facial expressions override their body gestures in video lectures?

While teaching, instructors will use unplanned, spontaneous facial expressions and body gestures to express their emotions. There is a growing consensus that an instructor's emotional expressions can trigger students' emotional and psychological responses, thus enhancing or inhibiting their learning in both face-to-face and online teaching contexts. However, little systematic research exists on which specific design features of an instructor's movements can induce emotions in video lectures. Three experiments were conducted in this study. Experiment 1 aimed to test the congruency/incongruency effects of an instructor's facial expressions (happy vs. bored) and body gestures (happy vs. bored) on student learning from video lectures in terms of students' emotions, motivation, cognitive load, and learning performance. Results of Experiment 1 showed that the instructor's happy facial expressions induced more positive emotions, enhanced motivation, and improved learning performance in students than the bored facial expressions, regardless of the instructor's body gestures. Experiment 2 sought to build upon the unexpected finding from Experiment 1 by increasing the frequency of body gestures, seeking evidence from both self-reports and eye movements. Results of Experiment 2 showed that the instructor's happy facial expressions enhanced students' learning performance when the instructor did not use body gestures, but not when they used increased body gestures. Experiment 3 was conducted to further expand upon findings from Experiment 1 and Experiment 2. Results of Experiment 3 confirmed the emotion-motivational and cognitive benefits of the instructor's happy facial expressions. The results have implications for designing features of instructors in video lectures: if instructors are visible, they should be encouraged to exhibit happy facial expressions, using body gestures less frequently or even avoid body gestures entirely. • An instructor's happy facial expressions induced students' more positive emotions, compared with the bored face. • An instructor's happy facial expressions enhanced students' motivation, compared with the bored facial expressions. • An instructor's happy facial expressions in isolation from body gestures directed students' more attention to the slides. • An instructor's happy facial expressions accompanied by less frequent or no body gestures improved learning performance.