Churchland's Metamers

Paul Churchland proposed a conceptual framework for translating reflectance profiles into a space he takes to be the color qualia space. It allows him to determine color metamers of spectral surface reflectances without reference to the characteristics of visual systems, claiming that the reflectance classes that it specifies correspond to visually determined metamers. We advance several objections to his method, show that a significant number of reflectance profiles are not placed into the space in agreement with the qualia solid, and produce two sets of counterexamples to his claim for metamers. – 1. Introduction; – 2. Preliminary Explanations and Objections : Color spaces and solids; Visual metamers; Matching and appearance; Effect of light on appearance of objects; – 3. Churchland's ‘Canonical Approximation’ Hypothesis; – 4. Does the CA Cylinder House SSRs in Agreement with the Perceptual Color Solid?; – 5. Two Sets of Metameric Counterexamples : Three metameric grays; Three metameric yellows; – 6. Birds, Bees, and Anthropocentrism Redux. M.-M. V.