There have been a number of criticisms, based on visual processes, of the Australian view that colour is an objective property of the world. These criticisms have led to subjective theories about colour. These visual processes (metamers, retinex theory, opponent processes, simultaneous contrast, colour constancy, subjective colours) have been examined and it is suggested that they do not carry their supposed critical weight against an objective theory. In particular, it is argued that metamers don’t occur in nature and primate colour (...) vision evolved without metamers. Thus normal colour vision occurs without the problem of metamers. This argument, in conjunction with evidence against the critical roles of opponent processes and retinex theory in colour vision, is taken to suggest that colour can be given a photon energy/wavelengthrealism explanation. This proposal allows an account of the many microstructural bases of colour generation put forward by Nassau (1983). It is argued that neither disjunctive realism or reflectance realism are adequate objective explanations of colour. (shrink)

Based on the technique of pressure blinding of the eye, two types of after-image were identified. A physicalist or mind/brain identity explanation was established for a negative a AI produced by moderately intense stimuli. These AI's were shown to be located in the neurons of the retina. An illusory AI of double a grating's spatial frequency was also produced in the same structure and was both prevented from being established and abolished after establishment by pressure blinding, thus showing that the (...) location was not more central. The illusory AI was predicted from the known non-linearity in the retina and this is the first case of a clear cut type-type identity of a sensation and a neural process. Some implications for the concepts of the explanatory gap between neurology and consciousness and multiple neural realizations of conscious states and topic neutrality are discussed. (shrink)

Russell and others have argued that the real nature of colour is transparentto us in colour vision. It's nature is fully revealed to us and no further knowledgeis theoretically possible. This is the doctrine of revelation. Two-dimensionalFourier analyses of coloured checkerboards have shown that apparently simple,monadic, colours can be based on quite different physical mechanisms. Experimentswith the McCollough effect on different types of checkerboards have shown thatidentical colours can have energy at the quite different orientations of Fourierharmonic components but no (...) energy at the edges of the checkerboards, thusrefuting revelation. It is concluded that this effect is not explained by a superveniencedispositional account of colour as proposed by McGinn . It was argued that theMcCollough effect in checkerboards was an example of a local mind/body reduction, by which the different characteristics of identical colours falsifies revelation. This reduction being based on both physical and neurological mechanisms led to a clear explanation of the perceive phenomenal effects and thus laid a small bridge over the explanatory gap. (shrink)