On the links between visual knowledge and naming: A single case study of a patient with a category-specific impairment for living things

Why living things, such as animals, fruit, and vegetables, can pose recognition or naming problems compared to nonliving things for certain patients has intrigued neuropsychologists for a number of years. We report a further case study of a patient (SRB) with a category-specific impairment in naming living things, which occurred in naming from vision, taste, touch, and when auditory definitions stressed the visual properties of objects. In addition, SRB was particularly poor at retrieving the perceptual attributes of living things when asked to draw from memory, make perceptual comparisons, or name associated colours. In contrast to this: SRB's performance on standard tests of semantic memory was relatively unimpaired, although when asked to give definitions about living things (and faces) he showed interference effects from visually and semantically similar exemplars from the same category. Also, the problem in naming was not necessarily confined to living things, but also occurred with faces and when nonliving things had to be named at a subordinate level. We suggest that SRB was impaired on tasks requiring fine differentiation between the representations of objects with similar perceptual structures, allowing both base-level naming of nonliving things, and semantic categorisation tasks to be performed relatively well. In a follow-up study, after naming accuracy had recovered, we demonstrated a remaining problem in response latencies to living things. Thus, though performance may recover to some degree in such patients, residual difficulties can still occur.