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Centering biases in heterochromatic brightness matching
Maria Pereverzeva1, Davida Y Teller
1Department of Psychology, University of Washington, Seattle, WA 98195-1525, USA. mariape@u.washington.edu
Vision Research
|September 6, 2005
Summary
The centering bias in brightness perception is reduced when observers foveate stimuli, suggesting a post-retinal origin. This visual system bias affects heterochromatic brightness matches.
Area of Science:
- Visual perception
- Psychophysics
- Neuroscience
Background:
- The method of constant stimuli can lead to centering bias in heterochromatic brightness matches.
- This bias causes matches to skew towards the center of the tested luminance range.
Purpose of the Study:
- To investigate the source of the centering bias in visual brightness perception.
- To differentiate between retinal, retinotopic, and spatiotopic origins of this bias.
Main Methods:
- Used red squares (2 degrees) in a gray surround with two luminance ranges presented on a video monitor.
- Employed fixation and foveation conditions to alter retinotopic location of stimuli.
- Included a dichoptic foveation condition to further isolate the bias source.
Main Results:
- A simultaneous centering bias was observed in the fixation condition, with different brightness matches at distinct retinotopic locations.
- This bias was largely eliminated in the foveation condition.
- No centering bias was found in the dichoptic foveation condition.
Conclusions:
- The centering bias in brightness perception originates from a post-retinal but retinotopically organized level of the visual system.
- The bias is not caused by retinal processes or more central, spatiotopically organized ones.