title: A model for colour vision defect.
abstract: The Unique Green phenomenon whereby the wavelengths of light which are judged neither blue-green nor yellow-green show a distinct genetic polymorph. Amongst the males there is a clear bimodality whereas there is a near normal distribution amongst the females. The classification of the types of  person so produced breeds true apparently in the X-chromosome. This phenomenon now having been confirmed is impossible to fit into the strict Walraven model of colour vision without modification. The modification that would be used is discussed and it is shown that a number of other difficulties within the Walraven model model can also be resolved.
mesh_terms: D003118:Color Perception / Q000502:physiology*; D003117:Color Vision Defects / Q000235:genetics / Q000503:physiopathology*; D005260:Female; D008040:Genetic Linkage; D006801:Humans; D008297:Male; D008954:Models, Biological; D010786:Photoreceptor Cells / Q000503:physiopathology*; D013057:Spectrum Analysis; D014960:X Chromosome