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The subjective visual vertical and the perceptual upright
Richard T Dyde1, Michael R Jenkin, Laurence R Harris
1Centre for Vision Research, York University, 4700 Keele Street, Toronto, ON, Canada, M3J 1P3. dyde@hpl.cvr.yorku.ca
Experimental Brain Research
|March 22, 2006
Summary
Researchers developed the Oriented CHAracter Recognition Test (OCHART) to measure the perceptual upright (PU). This new method distinguishes PU from the subjective visual vertical (SVV), revealing how body and visual cues influence our sense of orientation.
Area of Science:
- Neuroscience
- Perception Science
- Human Factors
Background:
- The subjective visual vertical (SVV) traditionally defines 'up' using gravity.
- Optimal visual performance requires perceiving objects as 'right way up'—the perceptual upright (PU).
- Existing methods for measuring PU are limited.
Purpose of the Study:
- To introduce and validate the Oriented CHAracter Recognition Test (OCHART) for measuring the perceptual upright (PU).
- To compare PU and SVV under varying visual background and body orientations.
- To investigate how body, visual, and gravity cues are integrated to determine perceived upright.
Main Methods:
- Developed OCHART using symbol orientation (P/d) to assess PU.
- Measured SVV by assessing line rotation relative to gravity.
- Recorded PU and SVV in different observer postures (upright, inverted, supine) with manipulated visual backgrounds.
Main Results:
- SVV aligned with gravity; PU aligned with the body axis when cues conflicted.
- Both SVV and PU were influenced by body, visual, and gravity cues.
- Cue weighting for PU was predicted by cue reliability, unlike SVV.
Conclusions:
- OCHART is a novel, practical method for assessing PU, complementing SVV measurements.
- Findings demonstrate maximum likelihood estimation in combining information across reference frames.
- OCHART is suitable for studying visual and non-visual systems in diverse populations and environments.