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Rebecca Ijekah, Sean O'Neil, Michael Crognale; Spectral Sensitivity Functions Derived from Decrement Thresholds. Journal of Vision 2017;17(10):1182. doi: 10.1167/17.10.1182.
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© ARVO (1962-2015); The Authors (2016-present)
Spectral sensitivity functions derived from increment threshold (IT) data have long been used to reveal the presence of opponent color interactions. Narrow band stimuli presented for long periods on bright achromatic backgrounds produce spectral sensitivity functions with large contribution from opponent channels while smaller fields on dim backgrounds presented quickly, or with fast flicker, result in the luminosity function with little to no evidence for opponent interaction. Although IT derived functions have been studied extensively, little attention has been paid to spectral sensitivity functions derived from decrement thresholds, largely due to the technical challenges. Decremental sensitivities are interesting for several reasons: 1) many if not most of the differences between surface colors in the real world are produced by decremental changes as light is differentially absorbed by pigments; and 2) there are known asymmetries in the visual system between on- and off-pathways and between incremental and decremental responses within these pathways. We measured increment and decrement sensitivity functions in subjects under conditions designed to produce strong contribution from opponent pathways. Preliminary results reveal that in many subjects, increment and decrement derived spectral sensitivity differed systematically. In particular, it appears that the decrement sensitivity curves reveal less contribution from the L-M opponent inputs relative to the S-(L+M) input.
Meeting abstract presented at VSS 2017
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