Animals extract information from their environment through sets of sensory cells. The responses of these cells are processed by other cells in the animals'' nervous systems, but post-receptoral processing cannot add information. Hence optimal performance is set by the characteristics of receptors. Such thinking underlies a common argument put forth to compare the capabilities of animals with different receptors: since receptors determine the limits of performance, little or nothing need be known about post-receptoral processing to know an animal''s perceptual capabilities. The present set of experiments are designed to test the validity of this argument. For color vision, spectral sensitivity -- the ability to absorb light as a function of wavelength -- is a receptor''s defining characteristic. Abnormalities in the set of receptor spectral sensitivities is the cause of most congenital color vision deficiencies in humans. If the response properties of receptors determine the limits of performance, then the capabilities of humans with different color vision phenotypes should be fully predictable from receptor spectral sensitivities alone. In this research, human subjects with various forms of color vision deficiency diagnosed through visual testing and DNA sequencing will be compared to others with normal color vision. Subjects will be asked to make perceptual judgments and will be tested for their abilities to make color discriminations. Both types of measure will be used to make inferences about the processing of information provided by the receptors. If post-receptoral processing can be neglected in characterizing color vision performance, then color vision deficiencies can be simulated by presenting normal subjects with stimuli that produce in their receptors the same responses that occur in the receptors of color vision deficient humans. If color vision deficiencies cannot be so readily simulated, one can conclude that the argument presented above - that receptor spectral sensitivities determine perceptual capabilities - is wrong. Such a finding would have major implications for the study of comparative color vision. This project will broaden minority participation by enabling the PI, himself of hispanic heritage, the opportunity to develop tools and acquire preliminary data that will make future grant applications more competitive. In addition, the PI will mentor interns in the California Alliance for Minority Participation, a program supported in part by the Louis Stokes Alliances for Minority Participation at NSF.
