Debi Roberson and Jules Davidoff
Department of Psychology
Goldsmiths College University of London
J.Davidoff@gold.ac.uk

Abstract A series of experiments investigated the nature and extent of the impairments to the structure of internal colour categories in a colour anomic patient (LEW). Initial findings indicated severe impairments. The patient sorted colour patches by choosing one at random and then looking for a second one that was the most perceptually similar to it. He then continued by taking the second patch and carrying out a similar operation; continuing in the same manner, he would cross category boundaries and thus fall victim to a version of the Sorites paradox. However, more detailed examination revealed that underlying categories appeared to be normal and that boundaries were intact. We conclude that lack of verbal coding would appear to render tasks with large numbers of different colour stimuli almost impossible for the patient to group or distinguish. The patient made normal (implicitly categorical) judgements over small colour distances but his lack of accurate verbal coding would appear to drastically impair such judgements with a large number of alternatives.