STRUCTURE AND FUNCTION IN THE LEXICAL SYSTEM - INSIGHTS FROM DISTRIBUTED MODELS OF WORD READING AND LEXICAL DECISION

The traditional view of the lexical system stipulates word-specific re presentations and separate pathways for regular and exception words. A n alternative approach views lexical knowledge as developing from gene ral learning principles applied to mappings among distributed represen tations of written and spoken words and their meanings. On this distri buted account, distinctions among words, and between words and nonword s, are not reified in the structure of the system but reflect the sens itivity of learning to the relative systematicity in the various mappi ngs. Two computational simulations address findings that have seemed p roblematic for the distributed approach. Both involve a consideration of the role of semantics in normal and impaired lexical processing. Th e first simulation accounts for patients with impaired comprehension b ut intact reading in terms of individual differences in the division o f labour between the semantic and phonological pathways. The second si mulation demonstrates that a distributed network can reliably distingu ish words from nonwords based on a measure of familiarity defined over semantics. The results underscore the importance of relating function to structure in the lexical system within the context of an explicit computational framework.