Does Random Movements mean Random Results? Why Asynchrony in Experiments on Body Ownership does not Work as Intended

Research Background and Issues

• Identified Problems or Challenges: The paper highlights that asynchronous conditions, widely used in virtual reality (VR) research to validate the effects of virtual embodiment, lack sufficient theoretical validation and standardization. Moreover, the implementation of asynchronous conditions varies significantly, such as through delays, offsets, and pre-recorded actions, which may have differing impacts on embodiment effects and user experience.
• Significance: The sense of embodiment is a critical aspect of VR research, influencing applications ranging from cognitive abilities to the reduction of social biases. If asynchronous conditions fail to effectively disrupt the illusion of embodiment or introduce other experimental confounding variables, the validity of current related experiments may be called into question.
• Research Motivation and Related Work:
  • The use of asynchronous conditions is based on classical psychological experimental methods, such as the "rubber hand illusion," which are not fully adapted to VR environments.
  • Existing literature lacks systematic comparisons of asynchronous implementation methods, with limited understanding of the reasons behind inconsistent effects and insufficient discussion on how to better standardize asynchronous conditions.

Solution

• Proposed Methods or Solutions:
  • Conduct two experiments: a quantitative study to examine the impact of asynchronous conditions on embodiment scores, user experience, and virtual sickness; and a qualitative study using the "think-aloud method" to explore user experiences of asynchronous embodiment.
  • Categorize asynchronous conditions into different types, such as delays, positional offsets, and pre-recorded actions, and establish a conceptual framework for comparison.
• Innovations:
  • Systematically compare the effects of different implementations of asynchronous conditions on virtual embodiment.
  • Propose specific impacts of asynchronous conditions on user movement, attention, emotions, and cognitive load, extending beyond the current reliance on questionnaire-based empirical research.
• Implementation Steps and Key Techniques:
  • Quantitative Experiment: Use Meta Quest headsets to collect data on embodiment perception (Avatar Embodiment Questionnaire), user experience (System Usability Scale), and virtual sickness (Virtual Reality Sickness Questionnaire).
  • Qualitative Experiment: Employ the "think-aloud method" and semi-structured interviews to record and analyze users' immediate experiences under each asynchronous condition.
  • Conceptual Framework: Define asynchronous conditions based on differences in temporal synchronization (synchronization delay) and spatial synchronization (positional offset) within a two-dimensional space.

Research Outcomes

• Specific Findings:
  • The quantitative experiment revealed that asynchronous conditions do not always effectively disrupt the illusion of embodiment. Pre-recorded actions had the most significant disruptive effect but resulted in the lowest user experience scores, while delayed actions showed no significant difference in embodiment scores compared to synchronous conditions.
  • The qualitative experiment uncovered how asynchronous conditions influence users' emotional experiences, movement patterns, attention allocation, and cognitive load. For example, users under delayed conditions actively slowed their movements to match the virtual body.
  • In some cases, asynchronous conditions even maintained the illusion of embodiment, as users mimicked the virtual body's movements to sustain a sense of connection.
• Advantages Over Existing Solutions:
  • Provides systematic insights into the differences in effectiveness and user experience impacts between various implementations of asynchronous conditions.
  • The proposed conceptual framework and user experience findings offer valuable references for improving experimental validity in future studies.
• Experimental or Evaluation Results:
  • The "pre-recorded actions" condition was the most effective at disrupting embodiment (significantly reducing embodiment scores) but scored the lowest in user experience.
  • Delayed actions had the weakest impact on the illusion of embodiment compared to other asynchronous conditions, with no significant distinction from synchronous conditions.
  • The "think-aloud method" and interviews revealed that the effects of asynchronous conditions extend beyond disrupting the illusion, influencing emotional responses and users' functional evaluations of the virtual body.
• Limitations and Future Directions:
  • The experiments implemented only specific forms of asynchronous conditions, without in-depth exploration of different parameters (e.g., delay duration, degree of motion offset).
  • The experiments focused on head and hand synchronization, without addressing full-body embodiment. Future research could explore synchronization and asynchronous conditions in full-body embodiment environments.
  • It is recommended to develop new tools for objective measurement of virtual embodiment, such as physiological data or more detailed motion tracking, to complement subjective questionnaire data.

The findings of this study highlight the issues in the current use of asynchronous conditions in experiments, emphasizing the need for standardized tools and more robust validation. Such efforts are crucial for ensuring the scientific rigor and practical feasibility of virtual reality embodiment research.