Anticipating Physical Processes in VR: Environment Type and Scale Alter Temporal Expectations

Paper Title

Anticipating Physical Processes in VR: Environment Type and Scale Alter Temporal Expectations

Publication Info

• Topic area: Temporal expectations and physical process modeling in virtual reality (VR)
• Keywords: Virtual reality, temporal expectations, gravity-driven motion, spatial scale, mental imagery, internal models, immersive environments, time perception, physical dynamics, user experience

Background and Problem

• Problem / challenge: It is unclear whether internal models guiding temporal expectations in the real world transfer unchanged to immersive VR. Prior research has shown that time perception in VR can differ from reality, but the mechanisms and factors influencing these differences, particularly for physical processes, remain underexplored.
• Significance: Understanding temporal expectations in VR is crucial for designing coherent and predictable VR systems, especially for applications involving time-critical interactions, training, and physics-based simulations.
• Motivation and related work: Previous studies suggest that VR can distort time perception (e.g., time compression) and alter expectations about physical processes, but these findings are limited to specific contexts and lack systematic exploration of fundamental physical laws like gravity. Additionally, spatial scale in VR has been shown to influence temporal judgments, but its effect on dynamic physical processes remains unclear.

Solution

• Proposed approach: Two experiments were conducted to investigate how immersive VR and its spatial scale affect temporal expectations for gravity-driven motion. Participants imagined a ball rolling down ramps in real and virtual environments and produced the expected durations.
• Novelty:
  1. Demonstrates that VR alters temporal expectations for gravity-driven motion compared to real environments.
  2. Shows that spatial scaling in VR biases temporal expectations, with larger virtual spaces eliciting longer imagined durations.
  3. Reveals that participants incorporate gravitational acceleration into mental simulations, though it is quantitatively underestimated.
• Procedure and key techniques:
  • Experiment 1: Participants imagined a ball rolling down ramps in a real lab, a 1:1 VR replica, and an up-scaled VR room. They produced the imagined durations, and the effects of environment type and spatial scale were analyzed.
  • Experiment 2: Participants indicated the imagined durations for the first and second halves of the ramps to assess whether gravitational acceleration was incorporated into their mental simulations.

Results

• Concrete findings:
  • Imagined durations were shorter in VR than in the real lab (e.g., VRnormal: 1.02 vs. RE: 1.07 mean ratio).
  • Larger virtual spaces (VRlarge) led to longer imagined durations compared to smaller ones (VRnormal).
  • Participants incorporated gravitational acceleration into their mental simulations, but the degree of acceleration was consistently underestimated (acceleration index < 2.4).
• Advantage over baselines: The study provides a systematic comparison of temporal expectations across real and virtual environments, including the novel effect of spatial scale on dynamic physical processes.
• Experiments / evaluation:
  • Experiment 1: 41 participants imagined ball motion across three environments (RE, VRnormal, VRlarge). Results showed significant effects of environment type and spatial scale on imagined durations.
  • Experiment 2: The same participants imagined durations for ramp halves, revealing consistent but underestimated incorporation of gravitational acceleration across environments.
• Limitations and future work:
  • Variability in mental imagery introduces inter-subject differences; future studies could increase sample size and trial numbers.
  • The absence of a large-scale real environment limits the interpretability of medium- and scale-related effects.
  • Future research should explore how implemented VR physics and prior VR experience influence temporal expectations.

Summary

This study investigates how immersive VR and its spatial scale affect users' temporal expectations for gravity-driven motion. Results from two experiments show that VR alters these expectations, with shorter imagined durations in VR compared to real environments and longer durations in larger virtual spaces. Participants incorporated gravitational acceleration into their mental simulations, though it was underestimated. These findings highlight that temporal expectations in VR are shaped by the medium and spatial context, providing insights for designing coherent and predictable VR experiences. Future work should explore how implemented physics and user experience influence these expectations in interactive VR scenarios.