ABSTRACT
The neural basis of colour vision appears to be well-established. This chapter shows an experiment which was designed to establish whether the two patients, HJA and WM could process colour information. This experiment yielded clear evidence of unconscious colour processing in both patients, but suggested that one patient was using a residual parvocellular system, whereas the other was using a non-parvocellular system. A brightness non-additivity test was also carried out on both patients, in which the brightnesses of red and green fields were matched to a yellow field. The reds and greens look brighter than a yellow at the same luminance, and this is assumed to be a particular feature of the parvocellular, opponent system. This prediction was upheld, sustaining the hypothesis that the latter patient had no functioning parvocellular system that could process colour information. Several further experiments were performed on this latter patient.
