Psychobiology of speech development: coemergence of language and a movement system.

Speech development in the child represents the coemergence of language and a movement system. This paper presents seven basic principles on which a theory of speech development should be formed. Briefly, these principles address developmental changes in musculoskeletal and neural anatomy, continuities in phonetic development, coordination of productive (motor) and perceptual capabilities, rhythmic or cyclic patterning of movement, changing units of phonologic contrast, and interaction of phonetic development with acquisition of a motor skill for speech. These basic principles are in harmony with an autoorganizational theory of language development in which the infant generates, maintains, and transforms patterns of order. Examples of developmental patterns are taken from the literature to illustrate the explanatory value of the autoorganizational theory.