Pre-service teachers' positive emotions enhance learning of students with low prior knowledge.

Introduction: Recent studies have suggested that teachers' emotions and emotional expressions play an important role in shaping students' learning experiences. However, existing research has primarily relied on self-reported measures, providing limited direct evidence regarding how pre-service teachers' emotional expressions influence learning performance and the underlying interpersonal processes during instruction. Method: This study examined whether students' prior knowledge moderated the eects of pre-service teachers' positive emotional expressions during face-to-face instruction. Using a dyadic fNIRS approach, it examined students' learning performance, interpersonal brain synchronization. Results and discussion: The findings revealed an expertise reversal eect: students with lower prior knowledge demonstrated improved learning performance, increased IBS in temporal regions, more positive emotional experiences, and higher learning motivation when exposed to pre-service teachers' positive rather than neutral emotional expressions. In contrast, students with higher prior knowledge showed limited benefits from pre-service teachers' positive emotional expressions. These findings extend the expertise reversal eect to the domain of teachers' emotional expressions, while highlighting the importance of considering learner characteristics when examining emotionally supportive instruction.