Chapter 11 - Semantic Memory

Abstract

This chapter presents the theory of semantic memory. The Quillian semantic memory is a theory of human long-term memory, and second a series of computer simulations of certain types of language processing. A Quillian semantic memory consisted of a set of entries, interconnected with arbitrarily complex bindings. Each entry corresponded to a conceptual notion, including but not limited to things such as words and propositions. Each entry had associated with it a set of proximate bindings. All bindings had a unidirectional pointer to a predicate and some number of unidirectional pointers to values. The predicates and values in bindings are all entries in the semantic memory themselves. Quillian emphasized several structural aspects of this view of semantic memory. First, each attribute and value of each binding is itself an entry, with its own set of proximate bindings. Second, there is no strict hierarchy in a semantic memory as a whole. Each entry is the root of its own hierarchy, but simultaneously is subsumed under an unlimited number of other hierarchies branching from other entries. Third, the chains of bindings leading away from a given root entry could refer back recursively to the root entry itself; that is, the entry canary could appear as an attribute or value of an indirect binding under the root entry canary. This chapter provides some key background information on semantic memory theory and research in normal and neuropsychological populations. The chapter begins with a description of the original Quillian model of semantic memory, including its structures and processes. The chapter describes generic semantic memory, the post-Quillian conceptions in wide use today. The chapter overviews some theoretical extensions, consequences, and divergences over the past several decades regarding semantic memory. The balance of the chapter focuses on (generic) semantic memory within the neuro literature: (1) five major neuro-related models of semantic memory are critically reviewed, (2) the issue of storage versus access deficits of semantic memory in neuropsychological populations are discussed, (3) empirical work on the use of similarity judgments to assess semantic memory organization in neuropsychological populations, specifically Alzheimer's disease (AD) is presented, and (4) research on the use of semantic priming to assess semantic knowledge in neuropsychological populations (specifically AD) is discussed. The chapter concludes by suggesting some intriguing topics for future research on semantic memory, with a focus on further interaction and collaboration between researchers in the behavioral sciences and those in the neuro-related sciences.