How important is seeing the face of the instructor?

Question

So, I am yet to make up my mind on which is a superior mode of teaching in flipped classroom videos:

1. Khan academy type model where you see slides or a digital drawing board and only listen to the instructor.
2. Or a video in which you see the instructor communicating with you. Maybe in one third of the video and the rest of the screen real estate is focused on graphics, video etc.

Let us assume that you have a superb communicator in both cases.

Which model is superior? Have there been any studies in this field?

Answer 1

I cannot cite studies, but extensive anecdotal observation (maybe 5,000 undergrad students, 500 grad students) suggests that about 1/4 of students do not need, or do not care, about the person who is the instructor. But a vast majority, perhaps 3/4, do care. There is a sense of needing/wanting reassurance from a person, and caring about the insights of a person. The lack of this need/want comes in (at least) two very opposite forms: obviously the oblivious/incompetent failure to see what's going on, but also the relatively-very-competent student who scarcely needs or wants reassurance and has better ways to spend their time. The middle ground seems not to exist.

So, operationally, for almost all purposes, the person who is the teacher matters, whether or not they are a truly wonderful teacher (as long as they're not completely inert as a human being).

(The "funny case" is the few students, both at undergrad and graduate levels, who for some reason expect/demand the teacher to be an automaton, reciting a text, not looking at students, not caring about students, not contributing, not critiquing, not improving. Yet they come to class rather than read the book? Maybe in anticipation of "books on tape", to have the classic text read to them out loud, in a room with other people?)

(The aspect of trusting in the expertise of the instructor seems, sadly, less relevant than the mandated understanding of their "authority". Tsk.)

Answer 2

Which model is superior?

That entirely depends on the metric you use to measure superior. I will assume that your primary interest is how much knowledge ends up sticking in your student's brain, i.e., you are measuring superior as better scores on learning outcomes.

In your scenarios, the main source of difference is the social presence of the instructor. The primary advantage of the scenario that uses a video of the instructor is that you can communicate through gesture and facial expressions. As I understand you question, this video is only used to supplement the audio; it won't carry any meaning by itself, but may be used to emphasize. This increased social presence will likely lead to higher engagement (as also observed by paul garrett's anecdotal evidence), but its effect on learning outcomes is less clear.

There is a nice meta-analysis that looks at general interfaces that either have or don't have an embodied agent (Yee et al. 2007); in other words, if it is useful to show the picture of a person, and how realistic that picture should be. The authors find a significantly larger effect of embodiment on subjective measures ("did you think you learned more?") than on objective measures ("What was your course grade?"). They also find a generally low effect of embodiment.

More close to this question, there exists a study by Kizilcec et al. that investigates almost what you are asking. The authors performed experiments on MOOC courses on Coursea (not a flipped classroom, but close enough). One version of the course videos had audio and slides only, the other had an added talking head in the corner of the screen.

In short, the authors find in a first observational study that, if a head is present, students think they need to exert less effort, and learn more, while also rating the experience as more positive when comparing to the version without a head. However, in a following experimental study, when comparing always showing a head to strategically showing a head for some (~30%-60%) videos, no difference on course grades or likelihood of taking assignments is found. The authors did find an effect on cognitive load, which seems to be influenced by the (visual vs. verbal) preference a of the individual learner. This appears consistent with the results of the meta-analysis on embodied agents for interfaces.

My opinion is that the direct effect of a video of the presenter on learning outcomes is likely too small to be of practical relevance; then again it might increase engagement just enough to get students to watch the video that would have otherwise not watched it.

Answer 3

Audio stimulates one sense, video stimulates two. One sense may suffice for some material, but not for others. Equally, one sense may be necessary, e.g., some material thrives as a podcast, but wouldn't as a video. For highly technical content, I'd need video to provide information rich visuals to support the audio, others could perhaps digest the material with just the audio. (Albeit, I suspect the video's audio wouldn't suffice for many and audio-only delivery would require audio to be prepared for that purpose.)

^{Note: A comment suggests the OP is not comparing video lectures to audio-only lectures. Yet, the title (How important is seeing the face of the instructor?), bounty (...additional effort and bandwidth needed for showing the instructor...), and question body (only listen[ing] to the instructor vs. a video) suggest differently. Nonetheless, the comment is plausible. Perhaps the OP can clarify.}