The Impact of Avatar Completeness on Embodiment and the Detectability of Hand Redirection in Virtual Reality

Title of the Paper

The Impact of Avatar Completeness on Embodiment and the Detectability of Hand Redirection in Virtual Reality

Paper Information

• Research Domain: Study of body perception and detection thresholds for hand redirection in virtual reality
• Keywords: Virtual reality, hand redirection, detection threshold, embodiment, illusion

Research Background and Problem

• Problem or Challenge:

  • Interaction techniques in virtual reality often rely on visual and hand position shifts (redirection), yet there is a lack of understanding of how these techniques affect user experience.
  • Most current studies focus on detection thresholds for "floating" hand models in virtual reality, neglecting whether more complete avatars are also applicable to hand redirection performance.

• Importance:

  • Hand redirection (HR) technology in virtual reality can enhance perceptual experiences but must ensure it does not interfere with users' avatar embodiment.
  • Avatar completeness may influence body perception and spatial awareness, thereby affecting the acceptability of hand redirection technology.

• Research Motivation and Related Work:

  • This study is driven by the trend of increasingly complete avatar representations in virtual reality, which are widely used in gaming, social interactions, and training. However, whether complete avatars reduce detection thresholds for hand redirection remains an unresolved question.
  • The authors propose two research questions:
    1. Does enhanced avatar completeness improve embodiment perception?
    2. Does higher embodiment reduce the detection threshold for hand redirection?

Solution

• Proposed Method:

  • An experiment was designed to investigate how avatar completeness affects users' embodiment perception and detection thresholds for hand redirection.
  • Four levels of avatar completeness were defined: Hand, Hand + Arm, Full Body, Full Body + Texture.

• Innovations:

  • Aiming to reveal whether more complete avatars, compared to floating hand models, result in changes to perceptual thresholds.
  • Utilizing standardized experimental setups and instruments to ensure high-precision measurements of hand redirection in virtual reality.

• Implementation Steps:

  1. Measurement of Embodiment Perception:
     • Users interact with avatars (mimicking gestures) to enhance embodiment perception.
     • Standardized questionnaires were used to quantify body ownership, agency, and spatial presence.
  2. Measurement of Hand Redirection Detection Thresholds:
     • Psychophysical experiments were conducted using a two-alternative forced choice (2IFC) method to evaluate users' ability to detect hand shifts.
     • Detection thresholds were compared across different levels of avatar completeness.

Research Findings

• Specific Results:

  • As avatar completeness levels increased, users' embodiment perception significantly improved.
  • Experimental evidence showed that the impact of avatar completeness on hand redirection detection thresholds was not significant, with detection thresholds consistent with previous studies on floating hands.

• Advantages:

  • This study validated the adaptability of existing hand redirection thresholds, regardless of avatar completeness, allowing continued use of current techniques and thresholds.
  • Provides user experience data to support the adoption of more complete avatars in virtual reality design.

• Experimental or Evaluation Results:

  • Embodiment Scores: More complete avatars resulted in higher body ownership perception.
  • Hand Redirection Detection Thresholds: Experimental results aligned with previous literature (e.g., hand shift direction measurements), showing no significant differences across avatar completeness levels.

• Limitations and Future Directions:

  • Limitations:
    • Avatar selection was limited to basic textured and robotic avatars, without considering the impact of personalized avatars on perception.
    • Fixed hand shift directions were used; further research is needed on different redirection trajectories or shift directions.
    • The current experimental scale was insufficient to reveal minor effects, requiring more precise equipment.
  • Future Directions:
    • Improve avatar selection schemes, such as using real 3D-scanned avatars or allowing users to customize avatars.
    • Evaluate other redirection parameters, such as shift distance, direction, and complexity.
    • Explore embodiment and technological compatibility when users interact with multiple avatars simultaneously.

Additional Information

• Author Statement: This study was funded by the German Data Foundation and the Singapore Ministry of Education Academic Research Fund.