Attention to cues and phonological categorization: Motor contributions

By Lisa Goffman


The acquisition of phonological units relies on perceptual and motor experiences and biases. Perceptual factors have been the emphasis of much research, with infants responding to prosodic and segmental cues in the input. Such perceptual sensitivities are thought to provide a mechanism for parsing important language units, such as words and sentences.
Motor contributions to the acquisition of production units have been less well investigated than perceptual. MacNeilage and Davis (2000) have argued that motor primitives associated with the syllable emerge in the context of canonical babbling and that the segmental content of these oscillatory open-close movements is detailed over the course of development. In adult speakers, Browman and Goldstein (1992) have developed the theory of Articulatory Phonology, in which movement primitives associated with each individual articulator (e.g., tongue body, lips, velum) are coordinated, with phonological units emerging from this coordination of gestures. Current models of language production (e.g., Levelt et al., 1999) include Articulation as an element, but do not develop how this processing level interacts with the phonological level, especially during acquisition.
The research discussed in this paper attempts to bridge this gap by measuring articulatory movement output as children and adults produce various language units. The working hypothesis is that motor capacities interact with phonological units and that these interactions change over the course of development. I incorporate methodologies from speech motor control and from psycholinguistics to assess how grammatical, lexical, and phonological processing levels are linked to articulatory output.
In this work I recorded oral articulatory movements (using the Optotrak system) while children and adults produce different segments, syllables, words, and sentences. The patterning of oral movements is assessed across these different speech production tasks, as well as the variability of such patterning. Three groups of results (i.e., segmental, prosodic, and semantic) are summarized. In the segmental domain, changes in a single phoneme influence the oral movement patterning of a single articulator (Goffman & Smith, 1999). Further, changes in a single segment exert broad coarticulatory effects that cross word and phrase boundaries. Another group of findings focuses on prosody, demonstrating that children produce late developing (in English) prosodic structures with relatively stable and small and short articulatory movements. Early developing trochees are, counter-intuitively, produced with relatively poorly controlled and variable articulatory patterns (e.g., Goffman, 1999; Goffman, Heisler, & Chakraborty, 2006). That is, stress patterns that are acquired relatively early for English-learning children are actually produced with less motor precision. It may be that children either omit syllables or produce equal stress in their attempts to produce more precise iambs. Finally, data will be presented showing that 4-year-old children produce more stable articulatory movement patterns when a novel phonetic form is provided with a visual or functional referent. All of this work together provides clues into how articulatory cues contribute to children’s developing phonological units.