Luminance-dependent hue shift in protanopes.

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dc.citation.volume21
dc.contributor.authorBimler DL
dc.contributor.authorParamei GV
dc.date.accessioned2008-04-01T03:49:47Z
dc.date.accessioned2016-03-06T22:25:24Z
dc.date.availableNO_RESTRICTION
dc.date.available2008-04-01T03:49:47Z
dc.date.available2016-03-06T22:25:24Z
dc.date.issued2004
dc.description.abstractFor normal trichromats, the hue of a light can change as its luminance varies. This Bezold-Brücke (B-B) hue shift is commonly attributed to nonlinearity in the blue-yellow opponent system. In the present study, we questioned whether protanopes experience analogous changes. Two protanopes (Ps) viewed spectral lights at six luminance levels across three log steps. Two normal trichromats (NTs) were tested for comparison. A variant of the color-naming method was used, with an additional "white" term. To overcome the difficulty of Ps' idiosyncratic color naming, we converted color-naming functions into individual color spaces, by way of interstimulus similarities and multidimensional scaling (MDS). The color spaces describe each stimulus in terms of spatial coordinates, so that hue shifts are measured geometrically, as displacements along specific dimensions. For the NTs, a B-B shift derived through MDS agreed well with values obtained directly by matching color-naming functions. A change in color appearance was also observed for the Ps, distinct from that in perceived brightness. This change was about twice as large as the B-B shift for NTs and combined what the latter would distinguish as hue and saturation shifts. The protanopic analogue of the B-B shift indicates that the blue-yellow nonlinearity persists in the absence of a red-green signal. In addition, at mesopic levels (< or = 38 td), the Ps' MDS solution was two dimensional at longer wavelengths, suggesting rod input. Conversely, at higher luminance levels (76 td-760 td) the MDS solution was essentially one dimensional, placing a lower limit on S-cone input at longer wavelengths.
dc.identifier.citationBimler, D. L.; Paramei, G. V. (2004). Luminance-dependent hue shift in protanopes. Visual Neuroscience. Vol. 21, No. 3, pp. 403-407.
dc.identifier.harvestedMassey_Dark
dc.identifier.harvestedMassey_Dark
dc.identifier.issn0952-5238
dc.language.isoen
dc.publisherCambridge
dc.relation.isbasedonVisual Neuroscience. Vol. 21, No. 3, pp. 403-407.
dc.relation.isformatofhttp://dx.doi.org/10.1017/S0952523804213013
dc.subjectBezold-Brücke hue shift
dc.subjectProtanope
dc.subjectColour naming
dc.subjectGeometrical model
dc.subjectNonlinearity
dc.subject.otherFields of Research::380000 Behavioural and Cognitive Sciences
dc.titleLuminance-dependent hue shift in protanopes.
dc.typeJournal article
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