Design of a Video Auditorium
Leveraging the Asymmetric Sensitivity of Eye Contact for Videoconferencing
Milton Chen, Stanford Computer Science
Seminar on People, Computers, and Design
Stanford University May 17, 2002
Remote classrooms often do not allow participants to see each other. A survey of Stanford faculty members and teaching assistants found that instructors dislike teaching students whom they cannot see. We built a multiparty videoconference system called the Video Auditorium. The instructor can see dozens of students on a wall-sized display and students can see each other on their PC. We conducted user studies and found that the optimal display size must balance two contradictory requirements: subjects prefer larger videos for seeing facial expressions and smaller videos for seeing everyone without head movement. Ideally, each video should have a field of view that spans 14 degrees, which corresponds to a slightly larger than life-size image. At the very least, each video should have a field of view of 6 degrees.
In our second user study, we measured how accurately people can perceive eye contact. We discovered that the sensitivity to eye contact is asymmetric, in that we are an order of magnitude less sensitive to eye contact when people look below our eyes than when they look to the left, right, or above our eyes. Additional experiments support a theory that people are prone to perceive eye contact, that is, we will think that someone is making eye contact with us unless we are certain that the person is not looking into our eyes. These experimental results suggest parameters for the design of videoconferencing systems. As a demonstration, we were able to construct from commodity components a simple dyadic videoconferencing prototype that supports eye contact.
The Video Auditorium is available for download at
Milton Chen is a PhD student within one year of graduation in Human Computer Interaction at Stanford. The title of his thesis is A Class-Scale Videoconferencing System: Design, Implementation, and Findings on Eye Contact, Frame Rate, and Video Size.
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