ABSTRACT
Long vaunted by philosophers as a possibly exhaustive set of classes among which all things might be distributed, “categories” were hardly considered as a potential principle of neural organisation until the concept of semantic memory was defined and elucidated in the original works of Tulving (1973) and Warrington (1975). Since that time, a large number of studies have reported broad category-specific effects in comprehension of verbal and visual stimuli. The most thoroughly debated category effect is that of the selective impairment of semantic knowl edge for living things (e.g., De Renzi & Lucchelli, 1994; Silveri & Gainotti, 1988; Warrington & Shallice, 1984). The reverse dissociation between preserved living things and relatively impaired man-made artefacts has also been observed, albeit less frequently (e.g., Hillis & Caramazza, 1991; McKenna & Parry, 1994; Warrington & McCarthy, 1987).
