Steven L. Buck

sbuck@u.washington.edu
Professor, Department of Psychology

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My long-term goal is to construct a generalized model of human visual pathways that includes signals from rods as well as cones. In the past I have examined the effects of rod-cone interaction on human visual sensitivity to flicker and increment detection, the role of both rod and cone signals in visual sensitivity regulation (adaptation), and the spatial dependence of these rod-cone interactions. My present research is focused on the issue of rod participation in the parallel set of cone pathways that mediate color vision. The goal is to develop a model of color vision incorporating the role of rods that accurately describes human perception and performance and that can be related to actual neural substrate. The approach involves sets of psychophysical studies of normal human vision coordinated with sets of physiological studies of primate retinal pathways. Examples of present psychophysical studies include:

1. Rod-cone color-mixture studies that determine the influence of rod signals in changing the hues produced by cone stimulation, especially the perceptual unique hues.
2. Scotopic color contrast (SC) studies that investigate the hues produced solely by rod signals (a) immediately after cone stimulation (successive contrast) or (b) adjacent to areas of cone stimulation (simultaneous contrast).
3. Wavelength discrimination studies that determine whether rod and S-cone signals oppose or augment each other in chromatic pathways that determine hue. Examples of physiological studies include the study of the interaction of rod and cone signals in the major classes of parvocellular-projecting ganglion cells, in AII amacrine cells, and in horizontal cells, all in the macaque retina.