Differences in gaze anticipation for locomotion with and without vision

Area of Science:

• Human locomotion
• Neuroscience
• Biomechanics

Background:

• Head and gaze direction spontaneously anticipate locomotor trajectory during human locomotion.
• This anticipatory behavior may optimize visual information selection and aid trajectory planning and motor control.
• Anticipation is hypothesized to persist in darkness, albeit with altered characteristics.

Purpose of the Study:

• To investigate the role of visual conditions (light vs. darkness) on the anticipatory behavior of head and gaze during locomotion.
• To quantify the differences in gaze and head anticipation between walking in light and in complete darkness.
• To understand the fundamental functions of gaze during self-motion and spatial perception.

Main Methods:

• 10 participants walked along predefined complex trajectories (limaçon, figure eight) in light and darkness.
• Whole-body kinematics were recorded using motion capture.
• Participant's right eye movements were tracked concurrently.

Main Results:

• Both in light and darkness, horizontal gaze anticipated head orientation, which in turn anticipated trajectory direction.
• Horizontal angular anticipation for both gaze and head was reduced by approximately half in darkness compared to light.
• Eye nystagmus properties (frequency, amplitude) were similar across visual conditions, but in light, nystagmus and head orientation shifted with trajectory direction.

Conclusions:

• Gaze and head movements exhibit anticipatory behavior during locomotion, crucial for self-motion representation and spatial perception.
• While anticipation persists in darkness, visual input significantly modulates its magnitude.
• Gaze plays a fundamental role in simulating future trajectories and stabilizing spatial perception, irrespective of visual conditions.