The Effect of Eye Contact in Multi-Party Conversations with Virtual Humans and Mitigating the Mona Lisa Effect

The demand for kiosk systems with embodied conversational agents has increased with the development of artificial intelligence. There have been attempts to utilize non-verbal cues, particularly virtual human (VH) eye contact, to enable human-like interaction. Eye contact with VHs can affect satisfaction with the system and the perception of VHs. However, when rendered in 2D kiosks, the gaze direction of a VH can be incorrectly perceived, due to a lack of stereo cues. A user study was conducted to examine the effects of the gaze behavior of VHs in multi-party conversations in a 2D display setting. The results showed that looking at actual speakers affects the perceived interpersonal skills, social presence, attention, co-presence, and competence in conversations with VHs. In a second study, the gaze perception was further examined with consideration of the Mona Lisa effect, which can lead users to believe that a VH rendered on a 2D display is gazing at them, regardless of the actual direction, within a narrow range. We also proposed the camera rotation angle fine tuning (CRAFT) method to enhance the users' perceptual accuracy regarding the direction of the VH's gaze.The results showed that the perceptual accuracy for the VH gaze decreased in a narrow range and that CRAFT could increase the perceptual accuracy.