Behavioural, electrophysiological and connectionist studies in inflectional morphology

Abstract

Theories of generative linguistics hold that language processing occurs by means of the manipulation of symbols by explicit rules. The past 15 years have seen the development of a radical challenge to this view, derived from a form of computational modelling called Parallel Distributed Processing or connectionism. Connectionist linguistic theory holds that language processing takes place at a subsymbolic level, and that the appearance of rule-driven behaviour is formed by the abstraction of patterns from the environment. The English past tense has become a critical arena of dissent between symbolic and subsymbolic theories of linguistics. There are two current dominant theories of past tense inflection: hybrid dual-route theory, championed by Pinker, posits a symbolic, explicit, default rule for the regularisation process, and an associative memory component for irregular exceptions; single-route theory maintains that regular and irregular inflectional morphology may both be accounted for within a single, subsymbolic, associative system which contains no explicit linguistic rules. This doctoral thesis describes a new classification of phonological similarity between verbs ('neighbourhood density'), which is used to develop mutually-exclusive and empirically-testable hypotheses from the two dominant theoretical perspectives of English past tense inflectional morphology. Empirical research is conducted in the domains of experimental psychology, electrophysiology and Connectionist modelling: four novel verb elicitation tasks are performed on adults; two ERP studies investigate brain activity for regular, irregular and novel verb inflection; and five neural network simulations are built in order to compare human data with network performance. Data are reported which have implications for single- and dual-route theories of past tense processing.