Cone photoreceptor sensitivities and unique hue chromatic responses: correlation and causation imply the physiological basis of unique hues

Ralph W. Pridmore

    Research output: Contribution to journalArticlepeer-review

    5 Citations (Scopus)
    14 Downloads (Pure)

    Abstract

    This paper relates major functions at the start and end of the color vision process. The process starts with three cone photoreceptors transducing light into electrical responses. Cone sensitivities were once expected to be Red Green Blue color matching functions (to mix colors) but microspectrometry proved otherwise: they instead peak in yellowish, greenish, and blueish hues. These physiological functions are an enigma, unmatched with any set of psychophysical (behavioral) functions. The end-result of the visual process is color sensation, whose essential percepts are unique (or pure) hues red, yellow, green, blue. Unique hues cannot be described by other hues, but can describe all other hues, e.g., that hue is reddish-blue. They are carried by four opponent chromatic response curves but the literature does not specify whether each curve represents a range of hues or only one hue (a unique) over its wavelength range. Here the latter is demonstrated, confirming that opponent chromatic responses define, and may be termed, unique hue chromatic responses. These psychophysical functions also are an enigma, unmatched with any physiological functions or basis. Here both enigmas are solved by demonstrating the three cone sensitivity curves and the three spectral chromatic response curves are almost identical sets (Pearson correlation coefficients r from 0.95-1.0) in peak wavelengths, curve shapes, math functions, and curve crossover wavelengths, though previously unrecognized due to presentation of curves in different formats, e.g., log, linear. (Red chromatic response curve is largely nonspectral and thus derives from two cones.) Close correlation combined with deterministic causation implies cones are the physiological basis of unique hues. This match of three physiological and three psychophysical functions is unique in color vision.
    Original languageEnglish
    Pages (from-to)e77134-1-e77134-13
    Number of pages13
    JournalPLoS ONE
    Volume8
    Issue number10
    DOIs
    Publication statusPublished - 2013

    Bibliographical note

    Copyright the Author(s) 2013. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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