Comparison of face-to-face and video-mediated interaction

A series of experiments are reported in which pairs of subjects performed a collaborative task remotely and communicated either via video and audio links or audio links only. Using the same task (the map task'), Boyle et al. (1994) found clear benefits of seeing the face compared with audio-only co-present interaction. Pairs who could see each other needed to say less to achieve the same level of performance as pairs who could only hear each other. In contrast to these findings, in all three experiments reported here, users of video links produced longer and more interrupted dialogues than those who had audio links only, although there were no differences in performance. Performance was affected when the video links were of low bandwidth, resulting in transmission delays. The drop in accuracy was correlated with a significant increase in levels of interrupted speech. We also compared the structure of dialogues and the use of gaze in high-quality video-mediated communication with those produced in face-to-face co-present interactions. Results show that both face-to-face and video-mediated speakers use visual cues to check for mutual understanding. When they cannot see each other such checks need to be conducted verbally, accounting for the length effect in dialogues. However, despite using visual cues in the same way as face-to-face speakers, video does not provide the same advantage of shorter and less interrupted dialogues. In addition, users of video gaze far more overall than face-to-face speakers. We suggest that when speakers are not physically co-present they are less confident in general that they have mutual understanding, even though they can see their interlocutors, and therefore over-compensate by increasing the level of both verbal and nonverbal information.