Phonology: a review and proposals from a connectionist perspective.

A parallel distributed processing (PDP) model of phonological processing is developed, including components to support repetition, auditory processing, comprehension, and language production. From the performance of the PDP reading model of Plaut, McClelland, Seidenberg, and Patterson (1996), it is inferred that the acoustic-articulatory motor pattern associator that supports repetition provides the basis for phonological sequence knowledge. From the observation that many patients make phonemic paraphasic errors in language production, as in repetition, it is argued that there must be a direct link between distributed concept representations (lexical semantic knowledge) and this network representation of sequence knowledge. In this way, both lexical semantic and phonotactic constraints are brought to bear on language production. The literature on phonological function in normal subjects (slip-of-the-tongue corpora) and in patients with aphasia is critically reviewed from this perspective. The relationship between acoustic and articulatory motor representations in the process of phonetic perception is considered. Repetition and reproduction conduction aphasia are reviewed in detail and extended consideration is given to the representation of auditory verbal short-term memory in the model. Finally, the PDP model is reconciled with information processing models of phonological processing, including that of Lichtheim, and with current knowledge of the anatomic localization of phonological processing. Although no simulations of the model were run, a number of simulation studies are proposed. Copyright 2001 Elsevier Science.