Multisensory Interactions in Head and Body Centered Perception of Verticality

Area of Science:

• Neuroscience
• Human Perception
• Sensory Integration

Background:

• Percepts of verticality are constructed from multisensory inputs, but cue weighting varies across studies.
• Understanding these variations is crucial for models of spatial orientation.

Purpose of the Study:

• To investigate how visual, somatosensory, and proprioceptive cues contribute to Head In Space (HIS) and Body In Space (BIS) representations.
• To explain discrepancies in cue weighting observed in previous research.

Main Methods:

• Participants performed Rod & Frame Test (RFT) and Subjective Postural Vertical (SPV) tasks while standing on a motion platform with controlled visual and body tilt.
• Perceptual judgments and postural responses were recorded to analyze multisensory integration for HIS and BIS.

Main Results:

• Both HIS and BIS percepts were influenced by body, head, and visual tilt.
• Visual tilt caused significant biases in the RFT task but minimal effects in the SPV task and postural responses.
• A dissociation in visual cue influence was observed between the RFT and SPV tasks.

Conclusions:

• A model explaining HIS and BIS percepts using direct and indirect sensory signals, corrected for perceived neck tilt, fits the data.
• Perception of HIS and BIS utilize the same sensory signals but with different weighting factors.
• Variations in cue weighting across studies likely stem from probing distinct spatial reference frames (head vs. body).