Interactions of color and luminance cues; Analysis of visual motion
The visual system can construct two largely separate maps of the world, using differences in luminance and differences
in color as the input information. Although these two maps are quite similar, they are not identical, and the ways in
which they vary can signal important characteristics of the visual world. Most of the work in our laboratory examines
the ways in which our ability to use color differs from our ability to use luminance, with particular emphasis on the
interactions of color and luminance cues when they are simultaneously present. We use psychophysical techniques
with human observers.
A primary current focus is on the analysis of visual motion by the luminance and chromatic systems. We have devised
objective methods that allow us to compare (and differentiate) the performance of two separate mechanisms that underlie motion
perception without resort to qualitative descriptions of perceptual phenomena. Using these tasks, we can determine the
conditions under which the luminance system analyzes visual motion in the same manner as does the chromatic system, and we
can distinguish the conditions under which it differs. We are now examining the mechanisms that underlie and produce the
differences.
We also continue a long-standing interest in general spatial and color vision mechanisms. We are studying the use
of spatial information based solely on color differences, the processing underlying color vision, and the spatial code
used in object recognition and other high-level perceptual tasks. Although low-level visual coding appears to be based on
something like a local spatial frequency analysis, our work suggests that it must be transformed into another (perhaps
explicitly spatial) code before perceptual decisions are made.
Selected Publications
Hardy, J. L. & De Valois, K. K. (2002) Color-selective analysis of luminance-varying stimuli. Vision
Res., in press.
Takeuchi, T., De Valois, K. K. & Motoyoshi, I. (2001) Light adaptation in motion direction judgments. J. Opt. Soc. Amer. A 18: in press.
Takeuchi, T. & De Valois, K.K. (2000) Modulation of perceived contrast by a moving surround. Vision
Res. 40: 2697-2709.
De Valois, K.K. (2000) Seeing. pp 1-392. K.K. De Valois (Ed.) In Handbook of Perception and Cognition. (2nd Edition) M. Friedman & E. Carterette (Series Eds.) San Diego: Academic Press.
Takeuchi, T. & De Valois, K.K. (1997) Motion-reversal reveals two motion mechanisms functioning in scotopic
vision. Vision Res. 37: 745-755.
De Valois KK: Spatial vision based upon color differences. (1994) In Lawton, TB (Ed.), Computational
Vision Based on Neurobiology. Proc. SPIE 2054: 95-103.
Zhang J, Yeh S-L & De Valois KK: Motion contrast and motion integration. (1993) Vision Res. 33:
2721-2732.
De Valois RL & De Valois KK: A multi-stage color model. (1993) Vision Res. 33: 1053-1065.
Kooi FL & De Valois KK: The role of color in the motion system. (1992) Vision Res. 32:657-668.
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