Gravity in the Brain as a Reference for Space and Time Perception.

Area of Science:

• Neuroscience
• Sensory Perception
• Human-Computer Interaction

Background:

• Spatial orientation and time perception are crucial for interacting with the environment.
• Gravity provides a ubiquitous reference for orientation (plumb line) and time calibration (gravitational acceleration).
• Historically, humans have utilized gravity-based tools like plumb bobs and clocks for measurement.

Purpose of the Study:

• To review behavioral evidence supporting the hypothesis that the brain utilizes gravity for spatial and temporal estimations.
• To explore how the brain integrates multisensory information with gravity for orientation and timing tasks.

Main Methods:

• Review of existing behavioral studies on spatial orientation and time perception.
• Analysis of how visual, vestibular, haptic, and visceral cues are combined to determine the visual vertical.
• Examination of computational models integrating multisensory signals with gravity for timing events.

Main Results:

• The brain merges various sensory cues (visual, vestibular, haptic, visceral) to estimate spatial orientation, with cue weighting task-dependent.
• An internal model of gravity's effects is combined with multisensory signals for accurate timing of object interception and navigation.
• The brain uses gravity-based models to assess motion duration and judge the naturalness of periodic movements.

Conclusions:

• The brain possesses inherent mechanisms to exploit gravity for estimating spatial orientation and the passage of time.
• Gravity serves as a fundamental reference, integrated with multisensory inputs, enabling sophisticated perceptual judgments.
• Understanding these mechanisms offers insights into sensory processing and potential applications in virtual environments and robotics.