Neuroscience 2000 Abstract
| Presentation Number: | 561.3 |
|---|---|
| Abstract Title: | Separating chromatic adaptation and simultaneous color contrast. |
| Authors: |
Wehrhahn, C.*1
; Teufel, H. J.1
1MPI für biologische Kybernetik, Tübingen, Germany |
| Primary Theme and Topics |
I. Neural Basis of Behavior - 105. Cognition: higher functions |
| Secondary Theme and Topics | F. Sensory Systems<br />- 77. Retina and photoreceptors |
| Session: |
561. Cognition: higher functions III Poster |
| Presentation Time: | Tuesday, November 7, 2000 3:00 PM-4:00 PM |
| Location: | Hall G-J |
| Keywords: | psychophysics, cones, adaptation, contrast |
When a large colored area surrounds a small white test field, human observers perceive it as colored. The color of the test field is shifted in the direction opposite to the surround color as expressed in a chromaticity chart. The interpretation of this observation in terms of chromatic adaptation and simultaneous color contrast is controversial. Within a chromaticity diagram discrimination between the two mechanisms is difficult (Smith & Pokorny 1996). Based on detection experiments we developed a new color metric and a set of equally bright color stimuli. When these are plotted on the plane of equal brightness in cone difference space as a function of the azimuth they are situated on a circle at equal angular distances (Teufel & Wehrhahn 2000). Use of these stimuli as sourrounds in binocular and dichoptic center-surround experiments enables us to discriminate between chromatic adaptation and simultaneous color contrast. A matching and a nulling procedure were used to measure induced shifts; both yield similar results. While we find no evidence for chromatic adaptation when testing our subjects in the binocular situation, we do observe local simultaneous color contrast. In the dichoptic situation the state of adaptation can be set for each eye individually. By specifying the stimulus on the basis of its azimuth as indicated above we quantified the relative strengths of L-and M-cone adaptation and simultaneous red-green contrast. We identified a rather strong contribution of global chromatic adaptation to the shift in the perceived color of the test field, but at the same time observed a substantial contribution of local simultaneous color contrast. The results are relevant to color constancy.
Supported by Deutsche Forschungsgemeinschaft
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2000 Neuroscience Meeting Planner. New Orleans, LA: Society for Neuroscience, 2000. Online.
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