Face Off: Evaluating Virtual Human Expressions and Non-Tracking Control Methods in VR

Social virtual reality (VR) applications have become more ubiquitous in recent years; central to this is the communication pipeline, how users perceive virtual human facial expressions, and how they control them in real time, especially when using VR devices without face-tracking. We investigated both aspects in a set of experiments. Firstly, we compared the perception of virtual human emotions on a traditional 2D screen and in VR. In a second experiment, we used a validated set of stimuli to compare three different control methods for manipulating an avatar's facial expressions in VR. These control methods utilize non-tracking control techniques, which do not rely on real-time face tracking but rely on alternative inputs via the VR controller. Our analysis shows that in VR, the effectiveness ratings for happy, sad, and surprise were significantly higher, and disgust was significantly more recognizable, compared to the screen. These findings contribute to our understanding of virtual human based emotional communication in VR by demonstrating that the perception of facial expression varies between screen and VR. Additionally, we identify raycast selection (point and click) as the most accurate control method, whereas thumbstick labeled (using a controller thumbstick with UI labels for guidance) was the fastest and most preferred method by participants.