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The Constancy of Colored After-Images
Semir Zeki1, Samuel Cheadle1, Joshua Pepper1
1Laboratory of Neurobiology, University College LondonLondon, UK.
Frontiers in Human Neuroscience
|May 26, 2017
Summary
The color of visual after-images does not depend on the light composition of a viewed patch. Instead, after-image color is determined by the ratio of light from the patch and its surroundings, suggesting later visual brain processing.
Area of Science:
- Visual perception
- Psychophysics
- Neuroscience
Background:
- Traditional theories explain after-images via retinal adaptation or physiological opponency.
- These models are insufficient for understanding after-image color in complex scenes.
Purpose of the Study:
- To investigate if after-image color depends on the specific wavelength-energy composition of light from a colored patch.
- To determine the factors influencing after-image color perception.
Main Methods:
- Conducted psychophysical experiments involving viewing colored patches within multi-colored scenes.
- Analyzed the relationship between light reflection properties and perceived after-image color.
Main Results:
- After-image color is independent of the wavelength-energy composition of light reflected from the patch itself.
- After-image color is determined by the ratio of light across different wavebands reflected from the patch and its surroundings.
Conclusions:
- Retinal adaptation and physiological opponency are inadequate explanations for after-image color.
- After-image color generation occurs later in the visual processing stream, after initial color generation in the brain.
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