Photorealistic self-avatars with facial tracking bring VR communication closer to face-to-face interaction, but also expose a fundamental limitation: people often lack accurate awareness and control of their own facial expressions. As a result, directly mirroring facial movements may not reliably convey users’ intended expressions in social VR. We propose modulating rendered expressions on avatars to improve social interaction in VR (e.g., exaggerating positive ones). To design effective modulation strategies and understand how modulation impacts user behavior and perception, we invited 18 participants to perform emotional expressions under varying modulation levels. We collected their self-reported ratings on accuracy and social appropriateness, as well as naturalness ratings and emotion recognition results from 18 additional observers who viewed the expressions. Results show that suppressing rendered expressions amplified participants’ actual facial movements, with effects differing by expression type. Based on our findings, we calculated the modulation ranges for different expressions and developed a real-time modulation system that exaggerates users’ facial expressions with a mild amplitude. We evaluated the system through a VR speech task where 12 participants delivered speeches with and without modulation. Results showed that the applied modulation improved emotional expressiveness and performance. Finally, we developed three application prototypes to illustrate the broader practical implications of our findings.

Virtual Reality (VR) enables users to engage with capabilities beyond human limitations, but it is not always obvious how to trigger these capabilities. Taking the lens of Affordance [35], we believe avatar design is the key to solving this issue, which ideally should communicate its capabilities and how to activate them. To understand the current practice, we selected eight capabilities across four categories and invited twelve professional designers to design avatars that communicate the capabilities and their corresponding interactions. From the resulting designs, we formed 16 guidelines to provide general and category-specific recommendations. Then, we validated these guidelines by letting two groups of twelve participants design avatars with and without guidelines. Participants rated the guidelines’ clarity and usefulness highly. External judges confirmed that avatars designed with the guidelines were more intuitive in conveying the capabilities and interaction methods. Finally, we demonstrated the applicability of the guidelines in avatar design for four VR applications.