Perception of Head Motion and Emotional Facial Expressions of Virtual Human Characters

  • Qiongdan Cao

Student thesis: Doctoral Thesis


It has been argued that character motion is important for virtual characters to engage users, especially for those virtual human characters with realistic rendering styles. For instance, study suggests that appropriate character motions can express emotional contents effectively and can make virtual characters look more human-like, and thus make these character more engaging. At the same time, current research explores that the level of engagement of a virtual character is related to user affinity, which is based on the Uncanny Valley theory. It describes the intensity of positive connections between users and virtual characters and thus influence user engagement.
However, unlike these well explored motions, such as body gestures and eye gaze, the effect of head motion, when appears alone and when combined with only facial expressions, stays unclear on the perception of emotional virtual characters.
Therefore, this research project explores the effect of head motion, either appearing alone or combining with only facial expressions, on the perception of a realistic rendering style virtual human character in different emotional situations in three key perceptual aspects: perceived motion realism, perceived emotional intensity, and user affinity, to investigate if head motion could help improving user engagement. Both fully immersive virtual reality environments and desktop screens will be used in this research project.
My study shows that head motion plays a critical role in affecting the perception of virtual characters, while some head motions can increase the perceived motion realism, perceived emotional intensity, and user affinity of the character in some emotional situations such as happiness and surprise. However, some head motions reduce the perceived motion realism of the character in angry emotional situation. Therefore, the head motion applied to those virtual characters should be accordingly based on specific emotional situations.
This research project suggests the use of "appropriate/effective” head motion is encouraged to enhance the effectiveness of facial expressions on improving user engagement for virtual characters, even when there is no sound/music or any other motions, such as body movement. Also, it provides a head range suggestion to animators about the recommendations of head motion range design for virtual characters to improve user engagement by inducing positive responses from users in three perceptual aspects.
It then opens a new research direction that suggest different “kinds/types” of head motion can influence the perception of virtual characters differently, while the effect is mainly based on the range/intensity of the head motion, and it’s combination with facial expressions.
Date of Award11 Jun 2024
Original languageEnglish
Awarding Institution
  • University of Portsmouth
SupervisorHui Yu (Supervisor), Paul Charisse (Supervisor) & Si Qiao (Supervisor)

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