Preserved thematic and impaired taxonomic categorisation: a case study

The present paper seeks to understand more about categorisation and its relation to naming. A patient with language impairments (LEW) was examined in a three-part investigation of his ability to make classification decisions. The first part demonstrated LEW's inability to make taxonomic classifications of shape thus confirming his previously documented impaired perceptual categorisation. The second part demonstrated that, despite LEW's inability to perform simple taxonomic classifications, he could reason analogically as well as a 4/5 year-old child. It is therefore argued that taxonomic classifications cannot be driven by the development of analogical reasoning. The third part more directly contrasted thematic and taxonomic classification. LEW showed a preference for thematic classification. In fact, there was no evidence of any substantial ability to make taxonomic colour classifications despite evidence for good preservation of the associated object-colour knowledge.