Projects
Driving & Space Judgments

Driving & Space Judgments

Overview

PERCEPTUAL EFFECT OF DRIVING: ADAPTIVE RESCALING OF PERCEPTION OF BODY AND ENVIRONMENT
📅 Aug 2015 – Apr 2016
🏛️ Center for Cognitive Science, IIT Gandhinagar
🎓 Supervised by Assoc. Prof. M. M. Sunny

This thesis empirically tested how embodying a vehicle in VR rescales intrinsic body-scale information, using aperture passability judgments as a metric. Through a rigorous Test-Manipulation-Test paradigm, we demonstrated that:

  • Driving induces perceived body widening
  • This rescaling persists post-driving
  • Affordance thresholds differ in Indian cultural contexts (1.1-1.3Ă— body width vs. Western 1.3 baseline)

Research Questions

  • Does driving a virtual car expand perceived body dimensions?
  • Is this rescaling persistent after disembodiment?
  • How do cultural movement patterns (e.g., navigating crowded spaces) affect affordance thresholds?
  • Can VR validly simulate body-extension experiences for perceptual studies?

Methodology

Pre-test → VR Driving → Post-test

  1. Pre-test:
    • Measured shoulder/hip width with custom caliper
    • Passability judgments for 8 real-world apertures (0.8-1.5Ă— body width)
    • Visual matching task for aperture size estimation
  2. Manipulation:
    • 45-min VR driving via Oculus Rift DK2 + Logitech G27 wheel
    • OpenDS simulation: Straight 20km road with 40 aperture obstacles (1.1-1.3Ă— car width)
    • Tracked collisions, lane changes, speed
  3. Post-test:
    • Repeated aperture judgments in real world

Technical Stack:

  • VR Setup: Oculus Rift DK2 (960Ă—1080@60Hz) + NVIDIA GTX 960
  • Simulation: OpenDS 3.5 with custom Blender 3D models (Peugeot 107 RHD)
  • Data Analysis: Python for timeline-to-distance conversion

Key Findings

  • Cultural Threshold Shift:
    Critical passability ratio = 1.1-1.3× body width (vs. Warren & Whang’s 1.3 baseline), attributed to Indian participants’ experience navigating crowded spaces.

  • Body-Schema Rescaling:

    • Post-driving aperture estimates 5.7% smaller than pre-test (p=0.02283)
    • Indicates persistent perceived body widening (Fig 13-14)
    • Effect strongest at 1.3Ă— ratio (p=0.057)

  • VR Embodiment Validation:
    Participants adapted to car dimensions within trials (↓ collisions, ↑ speed control) confirming functional rescaling during driving

  • Measurement Innovation:
    Custom body-width caliper addressed gender differences (hip vs. shoulder as widest point)

Impact

  • Theoretical: Confirms body schema plasticity during tool embodiment (extending Witt et al. 2005)
  • Methodological: Establishes VR protocol for studying persistent perceptual rescaling
  • Cultural: Challenges universal affordance thresholds (Stefanucci & Geuss 2009)
  • Applied: Informs VR training for drivers/operators of oversized vehicles

Key Contributions

  • First evidence of post-embodiment persistence in body-scale rescaling
  • Culture-sensitive affordance thresholds for aperture navigation
  • Open-source simulation framework (OpenDS + Blender pipeline)

Future Work

  • Reversal Test: Shrink body schema via constrained spaces
  • Control Group: Isolate practice effects from embodiment
  • Neural Correlates: fMRI of body schema during virtual driving
  • Safety Applications: Driver training for oversized vehicles

Key References

  • Stefanucci, J. K., & Geuss, M. N. (2009). Big people, little world: The body influences size perception. Perception, 38(12), 1782–1795.

  • Warren Jr, W. H., & Whang, S. (1987). Visual guidance of walking through apertures: Body-scaled information for affordances. Journal of Experimental Psychology: Human Perception and Performance, 13(3), 371.

  • Geuss, M., Stefanucci, J., et al. (2010). Can I pass?: Using affordances to measure perceived size in virtual environments. In Proceedings of the 7th Symposium on Applied Perception in Graphics and Visualization (pp. 61–64). ACM SAP.

Collaboration Opportunities

Open to discussion on methodology, data, or future directions. Happy to exchange ideas and explore new perspectives.