The mechanisms of phonemic paraphasia.

The mechanisms involved in the production of phonemic paraphasias are considered in this paper. Initially, a taxonomy of error types is provided where it is argued that there is a significant qualitative overlap in the kinds of errors witnessed in phonemic paraphasias and in segmental slips-of-the-tongue. There is ample historical precedent for the observation of this qualitative relation between fluent paraphasic errors and the phonemic errors in normal lapsus linguae. Some researchers have played down this qualitative similarity, but it is shown that when certain non-fluent aphasic phenomena are dissociated from the fluent paraphasias, the qualitative relation between paraphasias and slips remains entirely feasible. The metaphorical nature of the entire enterprise of characterizing phonemic paraphasias is briefly outlined, and finally the mechanisms at work are analysed from three rather different viewpoints: Merrill Garretts serial/hierarchical model of production; connectionist theory; and the phonological theory of underspecification.