Catch my Eyebrow, Catch my Mind: Examining the Effect of Upper Facial Expressions on Emotional Recognition for VR Avatars.

Capturing the movement of the upper face in social VR was challenging due to the head -mounted display's occlusion, which hinders accurate emotional expression. In this paper, we conducted two user studies to examine the effect of upper facial expressions on users' emotional recognition ability with VR avatars. Study 1 found that compared with eyelids, restricting the movement of eyebrows would yield greater difficulty for the users to recognize the expressed emotions of 3D avatars. Study 2 further tested different movement amplitudes of the upper facial expressions and results showed that the most realistic movement amplitude was optimal when balancing the tradeoff between emotion recognition accuracy and the Uncanny Valley effect.