Self-Motion Perception Influences Postural Sway More than Environmental Motion Perception.

Area of Science:

• Human postural control
• Virtual reality (VR) sensory integration
• Perception and motion

Background:

• Visual field motion influences postural sway and self-motion perception.
• The relative perceptual sensitivity to self-motion versus visual field motion in VR is not well understood.
• Methods to simultaneously quantify sway perception and actual sway are lacking.

Purpose of the Study:

• To investigate the relative perceptual sensitivity to self-motion versus visual field motion in VR.
• To determine if observable postural sway differs based on perceptual task (self-motion vs. visual field motion).
• To develop methods for quantifying sway perception alongside sway measurement.

Main Methods:

• Healthy adults stood in a VR environment experiencing virtual sinusoidal pitch rotation.
• Participants performed separate tasks: detecting room motion or increased postural sway.
• Head sway was tracked, and motion perception responses were analyzed using psychometric curves.

Main Results:

• Perception of room motion required significantly lower stimulus amplitudes (0.42°) than perception of postural sway (2.02°).
• Head sway increased significantly during and after visual stimulation, but only when participants perceived increased postural sway.
• Nearly 5-fold greater VR stimulus amplitudes were needed to perceive self-motion changes versus visual field motion changes.

Conclusions:

• Perceptual sensitivity to visual field motion is higher than to self-motion in VR.
• Observable postural sway is modulated by VR visual motion, but this effect is contingent on internal focus on self-motion.
• Head sway during VR motion is linked to perception only when focusing on self-motion, not external visual cues.