ABSTRACT
People carry various kinds of knowledge about concepts. For example, if you think of a dog, you will recall perceptual information (is four-legged, furry, barks), functional information (is used for hunting, guarding), associative information (is man’s best friend, likes to chase cats) and encyclopaedic information (is a mammal, of different breeds). Moreover, knowledge refers to specific conceptual categories, such as living and non-living things, body parts, proper names. In addition, knowledge is accessible from different input modalities (pictures, written words, spoken words, sound, touch or smell). Our long-term memory, responsible for the representation of the encyclopaedic knowledge of the world and the meaning of words and concepts, is usually called “semantic memory”, a notion first used by Quillian (1968) and further specified by Tulving (1972) (even if the issue was previously the focus of attention for many philosophers; see Eco, 1997). Semantic memory is often characterised in terms of what distinguishes it from “episodic memory”, which is the explicit recollection of facts that occurred at a particular time and place in one’s personal past, including their spatio-temporal relationship. It is precisely the lack of specific temporal and/or autobiographical information that characterises semantic memory. In remembering facts such as the capital city of Italy or the colour of an elephant, we have no awareness of the episodes during which these facts were acquired. The differentiation between semantic memory deficits and classic amnesic syndromes is
motivated by the different nature of these two types of disturbances. The term “amnesia” is usually applied solely to disorders involving events or episodes whereas, in the case of pathology of semantic memory, it is the general knowledge, rather than specific recollections with their spatiotemporal framework, which is assumed to be impaired. Semantic memory also differs from the lexical system (i.e. the union of the words known to each and every speaking person) as semantic memory also concerns information acquired in other ways, such as via the sense of smell or touch.
