John L. Locke

Linguistic significance of babbling: evidence from a tracheostomized infant

The role of babbling in language development is not well understood. One source of evidence is the utterances of infants who were tracheostomized during the period in which they would normally have produced syllabic vocalization. We describe here the phonetic patterns and linguistic development of a girl called Jenny. She was tracheostomized and generally aphonic from 0.5-1.8 but cognitively and socially normal, with near-normal comprehension of language. Acoustic analyses of Jennys utterances following decannulation revealed a tenth of the canonical syllables which might be expected in normally developing infants, an extremely small inventory of consonant-like segments, and a marked preference for labial obstruents. In these ways, she resembled a group of infants of the same age who also cannot hear their oral-motor movements, the congenitally deaf, suggesting that the audibility of babbling contributes to its onset. Two months following decannulation, when Jenny was 1.10, she produced only a handful of different words. We think this is because aphonia prevented her from discovering the referential value of vocal expression and discouraged the formation of a phonetic repertoire that could be appropriated for lexical service. This unusual case suggests that babbling normally facilitates the development of language and speech.

Genetic factors in the ontogeny of spoken language: evidence from monozygotic and dizygotic twins.

Recent controversy about the innateness of language has awakened interest in the genetic basis of linguistic development. In this study, we analysed more extensively data from Mather & Black (1984) in order to test the hypothesis that the speech articulation of monozygotic (MZ) twins would be qualitatively more similar than that of age- and sex-matched dizygotic (DZ) twins. Analyses revealed that 4-year-old MZ twin pairs were significantly more likely to misproduce the same sounds on an articulation test than were DZ twin pairs, and that DZ twins were no more likely to share errors than were children who were both genetically and environmentally unrelated. There was no evidence that MZ twins made more similar errors than DZ twins, and indeed it was difficult to make this determination since only broad categories of error (substitution, distortion, omission) were available for analysis. The greater amount of genetic material shared by MZ twins, and the presumably more similar morphology of their speech mechanisms, may have caused certain sound patterns to be of more nearly equal difficulty for both members of a MZ pair. However, these findings need to be confirmed with phonetically more detailed analyses.

Neural specializations for language: a developmental perspective

Abstract Human language is the way it is partly because it was learned by infants, and the mature brain has some of the properties it has because it developed epigenetically. To understand the neural bases of human language, we need a neurology of language development. Rather than focus on the maturation of structures associated with adult language, this perspective suggests that we study the development of brain mechanisms which function efficiently at every point along a developmental continuum that leads to linguistic competence. This behavioral growth path extends from the neonates orientation to indexical and affective aspects of the voice to the infants analysis of phonetic information that is embedded within the voice. Development of linguistic capacity requires the operation of two highly specialized information processing systems, one that is broadly configured to handle a variety of social-vocal and referential functions and one that is narrowly adapted for grammatical analysis and computation. Since linguistic capacity is produced by the joint action of these systems, this is what neurolinguistic theory must explain.

Editors' Overview on this special issue: “The Psycholinguistics of Writing”

In the last thirty years, research on the psychology of language has broached a number of practical problems relating to the comprehension of speech, print, sign, and several other codes. Parallel work on linguistic expression, with one significant exception, has moved forward in these areas as well. The exception, of course has been writing. In the last few years, as never before, there has been a surge of interest in writing. Some recent studies have dealt with the acquisition of expressive graphic systems and the teaching of writing skills, others have focused on the ways in which linguistic structure varies in speaking and writing, the processes by which thought is conveyed by print, and the impairment of writing processes in cases of neurological insult and dementia. This special issue, Psycholinguistics of Writing, collects research reports that deal with the development of writing, the improvement of writing skills in normal and in disabled populations, and the mechanisms underlying writing dysfunction. Developmental issues addressed include childrens discovery of the graphic system and increasing differentiation of writing from drawing (Tolchinsky-Landsmann and Levin), and the decreasing reliance on phonetic representation in spelling (Treiman). Two studies report on the use of microcomputers to improve childrens writing skills, one with ASL speakers (Prinz and Nelson) and one with junior high school students who receive computer-prompts to reread and revise (Daiute and Kruidenier). A study of patients with right-brain damage examines anomalies in their writing as compared to reading and drawing (Lebrun), and a neuropsychological mechanism and associated anatomic substrate for writing is proposed based on an analysis of agraphia as related to alexia and aphasia (Roeltgen and Heilman). Finally, the issue contains reviews of four major volumes on writing and writing development. The issue presents an invaluable resource of up-to-date, research-based approaches to understanding the psycholinguistics of writing by studying its development, the factors that relate to its improvement, and its breakdown.