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J. B. Nolan, S. Riley; Unique Hues, Color Naming, and Color Discrimination in a Low Vision Patient with a C203R Gene Mutation. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2733.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the experience of color and to detect whether the sensitivity of receptors will influence one's description of color, measurements of unique hues were taken. To explore how the phenomenological color world of a subject who possesses a C203R gene mutation matches that of color normal observers, and to assess whether the sensitivity of receptors will influence one’s description of color, two variations of a color naming procedure were utilized.
Our subject (JN) is a 32 year old male who exemplified 20/160 acuities and was diagnosed with Cone Dysfunction Syndrome. JN falls all plates in the Ishihara color test. Molecular genetic analysis (courtesy of M. Neitz and J. Neitz, Medical College of Wisconsin) was performed on JN to determine the type and numbers of the X-linked pigment genes and subsequently, a C203R gene mutation in a subset of the M genes was found. Unique Hue Measurements were taken requiring subjects to choose, from stimuli presented on a computer monitor, based on their "best" views of the hues "red", blue", yellow, and "green". A set of 424 Optical Society of America color "chips" (Boynton and Olson, 1987) served as stimuli in the color naming experiment for the subject and controls. For the color discrimination procedure the subject and controls (n=4) were tested using a standard pallet of nominal color regions.
Despite poor performance in color discrimination tasks, JN makes unique hue settings of blue and green that fall within the range of color normal control subjects. JN shows consistency in naming colors as well as characteristic shifts and confusions.JN shows much less consensus use of color terminology. While regions chosen by JN for the 11 basic color terms were large and slightly shifted, they were in rough agreement with controls.
These data imply that, despite his inability to pass most color tests, JN’s color naming ability is remarkably intact. Our unique hue results suggest that JN’s settings are within normal regions for some hues and only slightly out of normal range for others. Despite the fact that JN shows reduced cone function and color channel activity he shows consistency in naming colors as well as characteristic shifts and confusions. Color Categorization concurs with unique hue and color naming results. These data suggest a good degree of color constancy for JN. As the spectral composition of the light reaching the eye is altered, along with the appearance of the chip JN’s color naming ability remains mostly intact and consistent. These results suggest that a small photoreceptor complement may be sufficient for making unique hue settings, natural color discrimination, and color categorization.
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