The Dynamics of Meaning in Memory

"Semantics. The curse of man." Maxwell (1976, p. 19) "... how a word 'stands for' a thing or 'means' what the speaker intends to say or 'communicates' some condition of a thing to a listener has never been satisfactorily established" B. F. Skinner (1957, pp. 114-115) "... semantic structure of natural languages evidently offers many mysteries" Noam Chomsky (1965, p. 163) Meaning provides the fundamental bridge between the various language, cognitive, and perceptual components of the language comprehension system. As such, it is important to attempt to model how meaning can be acquired from experience and the specific nature of its representational form. In this chapter, we attempt to deal with the particularly difficult problem of how meaning can be specified. In particular, we are interested in how meaning can be represented in a computational model of meaning and the process by which these representations are formed. Although a review of previous models of word meaning would be outside the scope of this chapter (but see Komatsu, 1992), there are three psychological models that deserve mention because they have inspired current computational approaches in many ways. developed a hierarchical network model of semantic memory. It is a node and link model where knowledge is represented by both concepts (the nodes) and the relations among concepts (the links). Superordinate and subordinate relationships (hence, the hierarchical nature of the model) are represented via the links. The later version of the model, the spreading activation model (Collins & Loftus, 1975), de-emphasized the hierarchical nature of the mental representations in favor of a more general notion of semantic relatedness. The information retrieval process occurs as a function of spreading activation in the structured network. There has been considerable support for the model; the spreading activation approach to meaning retrieval and representation has been extensively used (see Neely, 1991, for a review). The notions of semantic connectedness, spreading activation, perceptual thresholds for conceptual retrieval are present in many more contemporary localist in their feature comparison model, hypothesized that there were two types of semantic features: defining features that were essential to the meaning of the concept and characteristic features that were usually true of the concept. Processing in this model hinged on whether an overall feature comparison or only a comparison using defining features was required for a semantic decision. The processing characteristics of both the spreading activation model and the feature comparison model have …