In an effort to enhance instruction and reach more students, educators design engaging online learning experiences, often in the form of online videos. While many instructional videos feature a picture-inpicture view of instructor, it is not clear how instructor presence influences learners' visual attention and what it contributes to learning and affect. Given this knowledge gap, this study explored the impact of instructor presence on learning, visual attention, and perceived learning in mathematics instructional videos of varying content difficulty. Thirty-six participants each viewed two 10-min-long mathematics videos (easy and difficult topics), with instructor either present or absent. Findings suggest that instructor attracted considerable visual attention, particularly when learners viewed the video on an easy topic. Although no significant difference in learning transfer was found for either topic, participants' recall of information from the video was better for easy topic when instructor was present. Finally, instructor presence positively influenced participants' perceived learning and satisfaction for both topics and led to a lower level of self-reported mental effort for difficult topic. (C) 2017 Elsevier Ltd. All rights reserved.