A SEMANTIC PROXIMITY EFFECT ON OBJECT RECOGNITION IN VISUAL AGNOSIA FOR BIOLOGICAL KINDS

Category specific visual agnosia (CSVA) for biological objects appears to be caused by a deficit in retreiving stuctural knowledge. We inves tigated the case of IL, a patient who suffers from CSVA, in order to e xamine the relation between structural and semantic knowledge. Two exp eriments involving synthetic shapes were conducted with IL: a visual d iscrimination task, which showed no perceptual encoding deficit; and a name-shape association task, which revealed a clear effect of semanti c proximity on visual recognition performance. The category specificit y of CSVA is explained by the greater semantic proximity between visua lly similar biological objects compared to artefacts.