Effect of avatar stylization and facial expression intensity in virtual interactions

Recently, with virtual reality headsets becoming increasingly accessible, interaction in virtual worlds has become more prevalent. While facial expressions are recognized for enhancing communication in face-to-face situations, the way they are perceived in virtual environments varies depending on avatars’ appearance and behavior. In this study, we investigated how the level of stylization and the intensity of facial expressions influence face-to-face interactions in virtual reality. We immersed 40 participants in a virtual environment where they had to communicate with an actress facing them during a guessing game. The actress’ avatar could adopt three levels of stylization (stylized, semi-realistic, and realistic) and three levels of facial expression intensity (reduced, unaltered, and augmented) using a gain system on sensors’ values. We assessed participants’ sense of social presence toward the actress-controlled avatar (co-presence, perceived affective understanding, and perceived emotional interdependence), as well as their perception of the avatar in terms of perceived realism, attractiveness, eeriness, familiarity, and trustworthiness. With regard to social presence, results indicated that participants felt a greater sense of co-presence with the stylized avatar than with the realistic one, regardless of the facial expression intensity. Stylization also impacted the scores of eeriness and trustworthiness, in favor of the stylized and semi-realistic avatars, with no interaction effect observed with the intensity of facial expressions. While the choice of stylization level remains a point for discussion depending on whether one focuses on social presence or avatar perception, we observe that increasing facial expressions had no negative impact on these two dimensions.