Eye Movements in Darkness Modulate Self-Motion Perception.

Area of Science:

• Neuroscience
• Perception Science
• Human Movement Science

Background:

• Humans use eye movements to stabilize vision during self-motion.
• The influence of these eye movements on self-motion perception is not well understood.
• Previous research has primarily focused on visual cues like optic flow.

Purpose of the Study:

• To investigate how eye movements affect the perception of self-motion.
• To quantify the contribution of eye-movement signals to self-motion perception.
• To determine if eye movements influence self-motion perception in the absence of optic flow.

Main Methods:

• Two experiments were conducted using a two-alternative forced choice task to judge passive lateral whole-body translations.
• Experiment 1 manipulated fixation conditions (world-fixed, body-fixed, free gaze) to constrain eye movements.
• Experiment 2 allowed free gaze and used oculomotor choice probability analysis to assess eye movement influence.

Main Results:

• Perceived translation duration was shorter when eye movements were constrained by a body-fixed fixation point compared to a world-fixed one.
• A linear model estimated eye-movement signals contributed approximately 25% to self-motion perception.
• Larger eye movement excursions during translation correlated with judgments of greater perceived motion.

Conclusions:

• Eye movements significantly influence the perception of self-motion.
• Oculomotor signals are integrated into self-motion perception, even without visual flow.
• This suggests a multimodal integration process for sensing body movement.