Black and White and Colour
What is it like to be a rod achromat? At night, or more concisely under low lighting conditions, the ordinary trichromat experiences the visual world by means of signals from the rods alone. This experience of the night ime world is commonly described as `seeing in black and white'. But if `seeing in black and white' describes the trichromat's visual experience under conditions of weak illumination, and if the visual experience of the rod achromat is a function of rod input under all lighting conditions, then the rod achromat must also see ``in black and white.'' Despite the intuitive nature of this line of reasoning, this conclusion is probably not correct. Through an exploration of the nature of luminance vision and albedo perception (the ability to see object surfaces as inherently light or dark), this paper explains why the dichotomy of `black and white or colour' is not a distinction that sits easily with the processes of human vision–and hence cannot be used to explain either the achromat's visual phenomenology or the trichromat's visual experience of the world at night.
KeywordsRetinal Image Surface Reflectance Luminance Cell Luminance Contrast Spectral Filter
I would like thank the James S. McDonnell Foundation through for the Foundation’s generous support through a James S. McDonnell Centennial Fellowship, without which this research would not have been possible. I would also like to thank Martin Hahn for reading and commenting on many drafts of this paper; Pete Mandik for his comments and helping to make this paper intelligible to the New York crowd, and; for their support and time, past and present graduate students, Jason Leardi, Lyle Crawford, Simon Pollon, Emma Esmaili, Nicole Pernat, Gerry Viera, and Robert Foley. Thanks to Richard Brown for organizing and facilitating the Consciousness Online conferences.
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