Preserved knowledge of maps of countries: implications for the organization of semantic memory.

We describe two patients with selectively preserved knowledge of the category of countries. Following a series of cerebral infarcts, patient DB presented with severe perceptual impairment, including dense apperceptive agnosia, prosopagnosia, and topographical agnosia. Despite these deficits, he could effortlessly name countries from their outline maps. Patient WH, who suffered from semantic dementia, had severe naming and comprehension difficulties, with extremely sparse residual semantic knowledge. Remarkably, the category of countries was preserved. First, we argue that, for both patients, this category preservation occurs at a semantic level. Second, we discuss our findings in the context of three current models of category-specific effects (perceptual, ontogenetic, and evolutionary models). We argue that the perceptual model (Humphreys and colleagues) cannot easily accommodate our findings. By contrast, the ontogenetic (Warrington and colleagues) and evolutionary models (Caramazza and colleagues) can ...