Abstract: Web-based and computer-assisted video learning is prevalent in college students and middle school students at present. However, there are still some issues that researchers are concerned about. Do we still need to present the image of the teacher in video learning? What characteristics of the teacher's image will affect video learning? This article reviewed the recent empirical studies on video learning in educational psychology, and explored the role of instructor in instructional video on learners’ learning performance and subjective feelings in the learning process from the aspects of eye gaze, gesture facial expression, and voice of the instructor. This review can help to explore what are the underlying factors that promote learning effectiveness in video learning.
The review found that, eye gaze may promote learning by guiding attention direction and promoting parasocial interaction. This study summarized the findings of previous studies and found that both guided gaze and direct gaze by instructors can improve learners'learning outcomes. In addition, the gestures exhibited by onscreen instructors mainly include iconic gestures, metaphoric gestures, deictic gestures, and beat gestures. Instructors’ gestures in the instructional video can not only guide learners’ attention to key learning contents, but also provide meaningful visual information for learners, promoting deeper cognitive processing of learners. We found that instructors'deictic gestures and iconic gestures can improve learners'learning outcomes. However, previous studies mainly focused on the instructors'positive facial expression influence on learning. Most studies have found the instructors'positive facial expression to improve the learners'perceived positive emotion, and improve the learning outcomes. Finally, both computer synthetic voice and human voice can facilitate video learning. It should be noted that whether using real human voice or computer synthetic voice, standard Mandarin should be adopted to avoid the confusion caused by accent to learners. At the same time, teachers should use the first-person and second-person speech styles to enhance learners'sense of involvement and participation, and try to use standard pronunciation.
Based on the conclusions of previous studies, this study also summarized the theoretical explanation of the influence of social cues on learning. Social cues may foster social bonds or direct attention. As for the foster social bonds, the theoretical explanation of instructor social cues influencing learning can be explained through social agency theory (SAT) and parasocial interaction (PSI) theory. Both SAT and PSI emphasize the positive effect of social cues on learning. The theory of PSI covers the influence of cognition, emotion, and behavior on learning, which posits that higher parasocial interaction promotes students’ responses to an instructor in a video, thereby improving students'learning outcomes. SAT also propose the instructional process of instructors in video-based learning as a social event. SAT suggests that the social responses or social cues (e.g., gestures, eye gaze) provided by human instructors during the learning process can trigger learners'cognitive schema of responding to people and activate deep cognitive processing strategies, thereby enhancing learners'transfer performance. As for the direct attention, the signaling principle provides an alternative explanation for how social cues facilitate learning. This principle suggests that cues serve to direct learners'attention to learning materials, which enables students to more rapidly select and process key information, thereby enhancing their learning performance.
In conclusion, we suggest that instructors use eye gaze (guided gaze and direct gaze), gesture (deictic gesture and iconic gesture), positive facial expressions, and first-person speech in video instruction to help learners focus their attention, better understand the content of teachers'verbal explanations, and enhance the interaction between teachers and students. Future studies need to further explore the mechanism of social cues effects in video learning, improve the theoretical hypothesis of social cues, disentangle the key factors of social cues, and explore the interaction effects of different social cues.

Key words: video learning, social cues, teacher image, eye gaze, gestures

摘要： 当前,基于多媒体的视频学习成为一种重要的学习形式。其中一个重要问题是：视频中是否需要呈现教师形象?教师的社会线索能否影响学习体验和学习效果?基于近期的实证研究,总结了教师的眼神注视、手势、面部表情和语音四种社会线索对视频学习的影响。结果发现,教师的眼神注视(直接注视、引导注视)能够引导注意、降低认知负荷、提高准社会交往,促进视频学习;手势(象征性手势、隐喻性手势和指示性手势)可以引导注意、降低认知负荷,改善视频学习;积极的面部表情和语调能提高准社会交往和积极情绪,促进视频学习。同时,教师应使用第一人称和第二人称的表达来增强学习者的参与感,并尽量用标准的口音。

关键词: 视频学习, 社会线索, 教师形象, 眼神注视, 手势