Axes of self-motion and object motion shape how we perceive world-relative motion

Area of Science:

• Visual perception
• Motion perception
• Virtual Reality

Background:

• Optic flow generated during self-motion requires flow parsing to perceive world-relative object motion.
• Depth and distance cues (size, binocular disparities) are present in real and VR environments.
• These cues may aid flow parsing when targets move in various directions.

Purpose of the Study:

• To investigate how depth and distance cues influence flow parsing during simulated self-motion.
• To examine the role of binocular disparity and object size in perceiving target motion relative to self-motion.

Main Methods:

• Two experiments using a wide-field stereoscopic environment with simulated self-motion.
• Participants indicated target motion direction relative to a large room or 3D object cluster.
• Controlled optic flow and motion vectors, varying target and self-motion directions (forward-backward, left-right).

Main Results:

• Flow parsing gains were lower for left-right targets during left-right locomotion.
• Flow parsing gains were higher for left-right targets during forward-backward locomotion.
• Overall gains were higher when self-motion and target motion were orthogonal compared to parallel.

Conclusions:

• Depth and distance cues are integrated during flow parsing for world-relative motion perception.
• The availability of depth and distance signals enhances the effectiveness of flow parsing.
• Orthogonal self-motion and target motion directions improve flow parsing effectiveness.