Self-motion perception from expanding and contracting optical flows overlapped with binocular disparity

Area of Science:

• Visual perception
• Neuroscience
• Human-computer interaction

Background:

• Vection, the sensation of self-motion, is crucial for understanding spatial orientation.
• The role of stereo depth in modulating vection remains incompletely understood.
• Previous research often focused on 2D motion cues, neglecting 3D spatial information.

Purpose of the Study:

• To investigate how stereo depth influences the induction and direction of vection.
• To determine whether background flow or retinal motion integration dominates heading perception.
• To explore the impact of disparity-defined flow fields on self-motion illusions.

Main Methods:

• Presenting expanding and contracting visual flows on different disparity planes to participants.
• Experiment 1: Assessing vection direction (forward/backward) with varying flow types and disparities.
• Experiment 2: Evaluating heading bias using dual expanding flows with offset centers of expansion.

Main Results:

• Background flow, defined by stereo depth, was the primary determinant of self-motion direction.
• Vection direction was consistently aligned with the dominant background flow, irrespective of retinal motion complexity.
• Heading perception was biased towards the center of the farther expansion when presented with dual expanding flows.

Conclusions:

• Stereo depth plays a critical role in generating robust vection illusions.
• Heading perception during vection is predominantly driven by the 3D structure of the visual scene (background flow).
• The brain prioritizes stereo depth cues over 2D retinal motion for self-motion estimation, highlighting the importance of 3D visual information.