Taxonomies in biology, phonetics, phonology, and speech motor control.

This article begins with a review explaining the different purposes of biological taxonomies. Taxonomic units are often dependent on the purpose for which the taxonomy has been constructed. Biological taxonomies provide an analogy that we use to emphasize some of the distinctions among the units of phonetic transcription systems, competence phonologies, and performance phonologies. The units of both phonology and phonetic transcription are considered as possible units of the speech motor system, and some of the difficulties of this assumption are explained. Although phonemic units, like units of phonetic transcription, are useful for many purposes, it is not theoretically necessary to use units derived as part of competence phonologies in systems attempting to explain phonological performance or speech motor performance. In this regard, we challenge the concept of coarticulation, because it is based on assumptions about the role of phonological or phonetic units in speech motor control. We offer an integrated perspective that has implications for research in speech motor control and deficits of the speech motor system. We see speech motor deficits as distinct from, yet possibly interacting with, phonological deficits.