When Hands Meet Physics in Virtual Reality: Effects of Interaction Fidelity on User Experience

Paper Title

When Hands Meet Physics in Virtual Reality: Effects of Interaction Fidelity on User Experience

Publication Info

• Topic area: Interaction fidelity in physics-based virtual reality systems
• Keywords: Virtual Reality, Interaction Fidelity, Physical Fidelity, Action Fidelity, User Experience, Sense of Embodiment, Task Performance, NASA-TLX, Interaction Quality, Gamified Tasks

Background and Problem

• Problem / challenge: Existing VR systems often lack standardized guidelines for balancing realism and usability in physics-based interactions. The interplay between hand-object dynamics and user experience remains underexplored.
• Significance: Understanding the trade-offs between realism and efficiency is critical for designing VR applications that balance immersion, usability, and task performance.
• Motivation and related work: Prior research has focused on technical implementations of physics simulations and their effects on plausibility and embodiment. However, studies have rarely addressed the joint effects of Physical and Action Fidelity on prolonged tasks. This paper builds on the Interaction Fidelity Model to systematically investigate these dimensions.

Solution

• Proposed approach: A controlled within-group study systematically varying Physical and Action Fidelity across three interaction conditions: No-Physics (NP), Object-Physics (OP), and Full-Physics (FP).
• Novelty:
  1. Introduced an interaction-focused perspective grounded in the Interaction Fidelity Model.
  2. Conducted a systematic empirical evaluation with 34 participants, measuring task performance, workload, embodiment, and interaction quality.
  3. Provided actionable design insights for VR applications based on trade-offs between realism and efficiency.
• Procedure and key techniques:
  • Participants performed 16 gamified tasks in a virtual garage environment under three conditions:
    • No-Physics (NP): No forces or collisions for hands and objects.
    • Object-Physics (OP): Objects obey physics, but hands do not.
    • Full-Physics (FP): Both hands and objects exhibit physical behavior.
  • Quantitative measures included task duration, NASA-TLX workload scores, and embodiment via the Virtual Embodiment Questionnaire (VEQ).
  • Qualitative data were collected through interviews and observations, analyzed using thematic analysis.

Results

• Concrete findings:
  • Higher Physical Fidelity increased task duration and workload but enhanced embodiment and interaction quality.
  • NP condition yielded the fastest task performance and lowest workload but lacked realism and body ownership.
  • OP condition consistently ranked lowest in interaction quality and user preference due to mismatched fidelity components.
• Advantage over baselines:
  • FP condition provided the highest embodiment (VEQ Acceptance scores: FP > NP, p=0.01) and interaction quality (CIQ Quality scores: FP > OP, p=0.007).
  • NP condition outperformed others in task efficiency (e.g., T7 task duration: NP < FP, p<0.001, r=0.82).
• Experiments / evaluation:
  • Conducted with 34 participants (ages 20–61, varying VR experience).
  • Tasks included pick-and-place, stacking, and button pressing, covering diverse hand actions.
  • Metrics: Task duration, NASA-TLX workload, VEQ subscales (Acceptance, Control, Change), and CIQ scores.
• Limitations and future work:
  • Excluded hybrid interaction metaphors (e.g., objects inheriting hand properties).
  • Used controllers instead of hand tracking due to technical limitations.
  • Future research should explore haptic feedback, full-body interactions, and the role of Presentational Fidelity.

Summary

This study systematically examined how varying levels of Physical and Action Fidelity in VR affect user experience. While higher fidelity enhanced embodiment and interaction quality, it increased workload and reduced task efficiency. Conversely, lower fidelity improved performance but limited realism. The hybrid OP condition suffered from mismatched fidelity, highlighting the importance of consistency. These findings provide actionable insights for designing VR systems tailored to specific application goals, such as prioritizing realism for immersive gaming or efficiency for productivity tasks. Future work should explore haptic integration, hand tracking, and additional fidelity components to further refine VR interaction design.