Early speech motor development: The influences of cognitive and linguistic factors.

摘要

Speech motor development progresses and regresses, possibly due to the interaction of cognition, language, and speech motor performance. Further knowledge regarding these relations would help inform a multifactorial, interactionist account of speech development. Oromotor behaviors of the lips and jaw were sampled and transduced using a three-dimensional motion capture system. Twenty-four infants were observed every three months, from 9 to 21 months of age. The relations of cognition and language variables to kinematic variables, such as movement speed, range of movement, and interarticulator coordination, were examined. Differences in the developmental course of three distinct oromotor behaviors (i.e., silent spontaneous movements, babbles, and words) were also investigated. Finally, the strength of the relations between the kinematic variables and cognitive and language variables was evaluated.;The first study found that speed and range of movement increased with age. Only the upper lip and jaw showed change in interarticulator coordination from 9 to 21 months. The increases in these variables are likely due to maturation of the speech motor system but may also reflect the influence of cognition and language formulation.;The second study found that trends for kinematic variables differed between silent spontaneous movements, babbles, and words. Spontaneous movements were generally slower than words, possibly due to the lack of auditory feedback or the need for cognition and language formulation. Speed differences between babbles and words in the upper lip may exist at some ages. These findings suggest that speech movements may reflect linguistic and cognitive processing demands and that the continuity hypothesis between babbling and words may be articulator-dependent.;The final study demonstrated significant associations between kinematic variables and standardized measures of language and cognitive skills. One possible reason for these findings is that cognition is represented in movement. Another may be that increases in underlying processes affect the three domains.;These studies provide fundamental knowledge about early speech motor development that will help motivate and guide future studies into the interaction of speech, language, and cognition.