Off-Vertical Body Orientation Delays the Perceived Onset of Visual Motion

Area of Science:

• Neuroscience
• Human Perception
• Vestibular System

Background:

• Perception of self-motion relies on integrating vestibular, visual, and body cues, typically in an upright posture.
• Off-vertical body orientations create sensory conflict, misaligning gravity-influenced signals and creating ambiguous vestibular information (tilt vs. translation).

Purpose of the Study:

• To investigate how manipulating body orientation affects the perceived timing of visual motion.
• To examine the impact of sensory conflict, arising from gravity and body position, on visual motion onset perception.

Main Methods:

• Participants performed temporal-order judgment tasks in virtual reality.
• Perceived onset of visual rotation (yaw axis) paired with an auditory tone was assessed in upright, supine, and side-recumbent positions.
• Sensory conflict was induced by altering body orientation relative to gravity.

Main Results:

• Perceived visual motion onset was delayed by approximately 30 ms in supine and side-recumbent positions compared to upright.
• No significant differences in timing estimates were found between non-upright orientations.
• Vestibular and body signal conflict negatively impacted visual motion timing perception.

Conclusions:

• Body orientation and gravity-induced sensory conflict significantly alter the perceived timing of visual motion.
• The perceived timing of visual stimuli is susceptible to mismatches in vestibular and proprioceptive information, even outside the plane of motion.