Early Word Production Research Articles

Maturing brain mechanisms and developing behavioral language skills

The relation between the maturation of brain mechanisms responsible for the N400 elicitation in the event-related brain potential (ERP) and the development of behavioral language skills was investigated in 12-month-old infants. ERPs to words presented in a picture-word priming paradigm were analyzed according to the infants’ production and comprehension skills as rated by their parents. Infants with high early word production displayed an N400 semantic priming effect already at 12 months. Infants with low early word production did not show this effect, not even for those words that parents rated to be comprehended by their child. The results suggest that the very early functioning of the neural mechanisms underlying N400 generation is related to the infants’ state of behavioral language development. The possible functional relation of the N400 neural mechanisms and the infant’s word learning ability is discussed.

Statistical frequency in perception affects children’s lexical production

Children’s early word production is influenced by the statistical frequency of speech sounds and combinations. Three experiments asked whether this production effect can be explained by a perceptual learning mechanism that is sensitive to word-token frequency and/or variability. Four-year-olds were exposed to nonwords that were either frequent (presented 10 times) or infrequent (presented once). When the frequent nonwords were spoken by the same talker, children showed no significant effect of perceptual frequency on production. When the frequent nonwords were spoken by different talkers, children produced them with fewer errors and shorter latencies. The results implicate token variability in perceptual learning.

Compensatory Vowel Lengthening for Omitted Coda Consonants: A Phonetic Investigation of Children's Early Representations of Prosodic Words

Children's early word productions often differ from the target form, sometimes exhibiting vowel lengthening when word-final coda consonants are omitted (e.g., dog /dog/ --> [d(c):]). It has typically been assumed that such minimal words lengthening compensates for a missing prosodic unit (a mora). However, this study raises the alternative hypothesis that vowel lengthening in early productions compensates for the missing coda segment. If lengthening selectively occurs with short/lax vowels but not long/tense vowels, this would provide support for the hypothesis that lengthening serves to preserve bimoraic or 'minimal word' structure. However, if lengthening occurs across the board, this would indicate that lengthening compensates for the omitted segment. In order to address this issue, matched word pairs produced with and without a coda were extracted from the spontaneous speech of three English-speaking children between the ages of 1 ;1 and 2;6. Phonetic analysis compared the duration of vowels in words with and without the coda. The results showed that two children lengthened both short and long vowels when the coda was omitted, whereas one child selectively lengthened only short vowels. The implications of these findings, both for the representation of prosodic words, and for theories of production more generally, are discussed.

Human Motor Behavior

Human Motor Behavior

Events at early development: Are they associated with early word production and neurodevelopmental abilities at the preschool age?

Background Obstetrical and neonatal complications and/or an adverse parenting environment are risk factors for language impairment, but little is known about their effects on early word production (late talking). Aims To determine obstetrical and neonatal risk factors in children with delayed word production; to assess the influence of the parenting environment on word production; to determine whether the toddler's vocabulary competence is related to his/her social competence; to document the neurodevelopmental outcome at the late preschool age. Study design Prospective follow-up study. Based on word production at 18 months, children were retrospectively classified into consistent or transient late talkers and controls. Subjects Full-term infants, N = 30 (mean GA 40.3 ± 1.1 weeks, mean birth weight 3577 ± 267 g) were assessed at 18 and 24 months; and 5 years and 7 months. Methods Austrian Communicative Development Inventories; Bayley Scales of Infant Development; Griffiths Developmental Scales. Outcome measures Peabody Picture Vocabulary Test; Kaufman Assessment Battery for Children; Touwen's neurological examination. Results and Conclusions Lower Apgar scores and the need for neonatal intensive care were associated with delayed word production. The parents' educational and vocational levels were lower in late talkers. Early vocabulary competence correlated with social competence. With regard to the prediction of lexical and cognitive outcomes, late talkers did not differ from controls. Minor neurological dysfunctions (MND) were seen in nearly half of the late talkers and indicate the necessity to follow these children into school age, when MND might become more obvious and literacy can be assessed.

Special Issue

Researchers have long known that children’s early word productions differ from those of adults, both in the segments and syllables produced (e.g., dog > [dɑ]; banana > [ n nə). Some have proposed that these early segmental /syllabic truncations are due to early perceptual or articulatory limitations (e.g., Echols, 1992; MacNeilage, 1980). Others have proposed that children’s early words are phonologically “unmarked,” becoming more marked over time (Demuth, 1995; Gnanadesikan, 2004). However, results from recent crosslinguistic research suggest that children’s early word productions are sensitive to language-specific phonologies, showing earlier acquisition of high frequency syllable and prosodic word structures (e.g., Levelt, Schiller, & Levelt, 2000; Roark & Demuth, 2000). This indicates that children’s early prosodic words show more systematic language-specific differences in shape than perceptual, articulatory and markedness proposals would predict. To the extent that these findings are robust, we should then be able to make predictions regarding the timing and course of prosodic word development across languages. The first goal of this special volume is to explore these issues more fully by bringing together recent research on the acquisition of prosodic words (PWs) from a number of languages with different distributions of prosodic structures. The papers in this volume therefore include contributions from the less studied Catalan (Prieto), European Portuguese (Vigario, Freitas & Frota) and Japanese (Ota), as well as the better-known Spanish (Lleo) and English (Demuth, Culbertson & Alter). In most cases newly collected longitudinal corpora, including data from several children between the ages of 1 – 2 years, now makes it possible to provide a more systematic, quantitative study of PW development. A second goal of this volume was to test some of the frequency-based predictions, providing a theoretical framework for further investigation of children’s developing phonologies. For example, frequency and markedness constraints often co-occur, facilitating the early acquisition of high-frequency, unmarked structures (e.g., core CV syllables, trochaic feet). Occasionally, however, the “unmarked” structure is not the most frequent, raising questions regarding the course of acquisition under such conditions (e.g., Stites, Demuth, & Kirk, 2004; Zamuner, Gerken, & Hammond, 2005). The existence of these new longitudinal acquisition corpora, many of which include extensive samples of early child-directed speech, now make it possible to LANGUAGE AND SPEECH, 2006, 49 (2), 129 –135

Word length in syllables: evidence from early word production in Finnish

This study examines the phonological form of ten Finnish-speaking children's productive vocabulary in the period of transition into speech, with primary focus on the number of syllables in a word. The results showed that Finnish children produced relatively few monosyllables and a large number of disyllables in their early words. This seemed to reflect the predominance of disyllabic target words over monosyllabic ones in Finnish. Furthermore, it appeared that the reduction of disyllabic words was very uncommon, whereas polysyllabic words were considerably more often deformed. Finally, the polysyllabic words were quite often truncated in such a way that they fitted a trochaic pattern, which may partly be due to the fact that primary word stress in Finnish falls on the first syllable. Additionally, the segmental content of the target word and the use of a favourite template may have an effect on the selection of syllables. Thus, the present results suggest that the target language affects the syllabicity of children's early word productions and that differences in the linguistic features of the input may influence the strategies that children use when producing their first words.

Phonological theory and the development of prosodic structure

This article presents a model of prosodic structure development that takes account of the fundamental continuity between child and adult systems, the surface level divergence of child forms from their adult target forms, and the overall developmental paths of prosodic structure. The main empirical base for the study comes from longitudinal data collected from three Japanese-speaking children (1; 0–2; 6). Evidence for word-internal prosodic constituents including the mora and the foot is found in compensatory lengthening phenomena, syllable size restrictions and word size restrictions in early word production. By implementing the representational principles that organize these prosodic categories as rankable and violable constraints, Optimality Theory can provide a systematic account of the differences in the prosodic structure of child and adult Japanese while assuming representational continuity between the two. A constraint-based model of prosodic structure acquisition is also shown to demarcate the learning paths in a way that is consistent with the data.

Is There a “Trochaic Bias” in Early Word Learning? Evidence from Infant Production in English and French

Studies of speech perception and segmentation in the prelinguistic period, early word production, and patterns of function word omission in early syntax have all recently emphasized the role of the trochaic accentual pattern in English, sometimes positing a universal trochaic bias. We make use of perceptual and acoustic analyses of words and babble from 9 children acquiring English and 5 acquiring French in the late single-word period (13-20 months) to provide a direct test for the existence of such a bias. Neither English nor French infant vocalizations were exclusively trochaic. The iambic productions of American infants were traced to the presence of iambic phrases in the input. Differences between English and French in the acoustic realization of accent in infant vocalizations were also traceable to adult patterns. However, the almost bipolar distribution of trochaic and iambic patterns in the data from English-learning infants was ultimately traceable to the integration of prosodic and segmental patterning in individual child word production templates, themselves arguably the product of an earlier acting articulatory filter.

Trochees and iambs in early word production

Trochees and iambs in early word production

External sources of individual differences? A cross-linguistic analysis of the phonetics of mothers' speech to 1-yr-old children.

Wide individual differences in early word production characterize children learning the same language, but the role of specific adult input in this interchild variability is unknown. Sampling the speech of American, French, and Swedish mothers (5 in each language group) to their 1-year-old children, this study analyzed the distribution of consonantal categories, word length, and final consonants in running speech, content words, initial consonant of content words, and target words (adult models of words attempted by the children) as well as the children's own early words (from age 9 months to about 18 months). Variability is greater in child words than adult speech, and individual mother-child dyads show no evidence of specific maternal influence on the phonetics of the child's speech

The Role of Vocabulary Development in Children′s Spoken Word Recognition and Segmentation Ability

This paper reviews research bearing on the development of spoken word recognition, from studies of speech perception in infancy and early word productions through investigations of word recognition proper and explicit phoneme segmentation ability in middle childhood. In contrast to the assumption of two prominent models of adult recognition (the cohort model of Marslen-Wilson, 1987, and the neighborhood activation model of Luce, 1986b), the bulk of the developmental research indicates that lexical representation and processing are not, at the outset, segmentally based; instead, they are more holistic in nature. Segmental restructuring of lexical representations begins largely with the "vocabulary growth spurt" in late infancy/toddlerhood and associated pressures for more detailed and efficient storage of lexical items. However, this restructuring is a protracted process that extends over the preschool years, because there is still substantial growth during this period in terms of overall vocabulary size and the familiarity of individual lexical items. Such continued vocabulary growth (and thus the dynamic nature of intra- and interlexical representations) dictates that the use of partial, word-initial acoustic-phonetic input does not always constitute a reliable basis for recognition, as it does for the adult. Extant variations in the segmental structure of basic lexical representations and/or the use of such structure for recognition in the preschool period may contribute to individual differences in explicit phoneme segmentation ability, and thus early reading success.

Variable paths to early word production

Variability, within and across subjects, provides a basis for the "selection" of a path into language use. Illustration of the extent of variation is drawn from children learning four languages and compared with analyses of the mothers' speech for one group. The organization of early word production patterns into an initial phonological system is traced for one of the children. It is hypothesized that an "articulatory filter" based on a child's familiarity with the auditory consequences of his or her own vocal patterns provides a mechanism for the first production of speech forms; a mechanism supporting the shift from babble to intentional vocal communication is also suggested.

Prespeech and early speech development of two late talkers

Speech samples of 34 children were analysed to determine patterns of babbling and early word productions from 9 to 24 months. The present study focuses on the vocal and verbal development of two 'late talkers' in the group who did not meet the criterion for achieving the Meaningful Speech Stage until 24 months. Analysis of these subjects' prespeech utterances revealed that one of them produced few canonical babbles from 9 to 21 months; the other displayed an unusual pattern of sound preference in his babbles. At 24 months, word productions of both late talkers evidenced more limited phonetic repertoires and simpler syllable shapes than those used by their peers. These findings suggest that atypical babbling may be associated with delays in the acquisition of meaningful speech.

Phonologically motivated substitutions in a 20–22 month old's imitations of intervocalic alveolar stops

Systematic deviations between early word productions and their adult targets reflect not only children's articulatory limitations, but also their phonological development. However, research in child phonology has overlooked an important source of information by excluding from analysis any direct imitations of adult words. Consistent with observations about syntactic and cognitive development, spoken imitations should be systematically modified by the child's phonological system. Imitation studies should thus reveal more about the sophistication of the early phonological system by minimizing demands on memory and lexical access, by allowing presentation of unfamiliar or nonsense words, and by permitting comparison of the child's productions with the actual phonetic and acoustic properties of the adult targets. The present research found remarkable phonological sophistication in a toddler's production of intervocalic stops, based on phonetic and acoustic analyses of her imitations of a set of phonetically reduced adult targets at 20–22 months of age. The adult targets were disyllabic words and nonwords containing /d/ or /t/ preceding 〈-er〉, 〈-le〉, or 〈-en〉, in which the stops were realized as the restricted phonetic variants [r], [dn], or [ʔ], (e.g., respectively, 〈wider〉 or 〈whiter〉; 〈widen〉; 〈whiten〉). Although alveolar stops are not normally produced in this phonetic environment, the child consistently substituted them for the more restricted variants found in the adult targets. The child's phonology also distinguished /t/ and /d/. The findings indicate a rule like that in the adult grammar which determines how these phonemes will be realized in highly specified phonetic contexts and, consequently, how phonetically disparate forms are related in an abstract category. The child's failure to exactly imitate the target utterances and the systematicity of her deviations further argue that the targets were, in fact, filtered through the child's phonology before she produced them. [Work supported by NIH.]

Play pen monologues: the interplay of words and babbles in the first words period

ABSTRACTA case study is presented of the babbling monologues produced by a Dutch child in the six weeks following acquisition of the first word. The relationship between word and babbling development is investigated. There appears to be a continuous interplay between both aspects of speech development: new words may influence the character and the course of babbling, whereas babbling in turn may give rise to phonological preferences for selecting other new words. It is concluded that the analysis of concurrent babbling may provide clues for explaining the highly variable phenomena of early word production.

A comparative study of common chimpanzee and human infant sounds

Chimpanzees observed in Tanzania produced a graded, dynamic sound system ranging from short distance, softer, lower F0 sounds to long distance, louder, higher F0 sounds. A softer and a louder sound category, the whimper and the scream, were selected for further study of F0 and harmonics. From these acoustic analyses and behavioral observations, evidence for a variety of phonatory and resonance patterns were evident in their vocalic sound system which could carry information but lack the segmental contrastivity of human speech. Human infants about a year old were audio and video recorded in the laboratory or home. Vocalic sound durations, F0 contours, and range were much more variable than those observed for chimpanzees. The F0 of human infant sounds often ranged from 300–600 Hz, although occasionally F0 values many times higher were produced making harmonic‐formant interactions a critical issue in the comparison with chimpanzee sounds. Fricative, stop, and other consonants not evident in chimpanzee sounds, were common in human infants at 13 months. Selection and reduplication of early word productions suggests the importance of self stimulation, caregiver responsiveness, imitation, vocal tract development, and the acquisition of species typical speech motor skills as some important prerequisites to the development of human words. [Support was provided by NIH, NSF and the A. von Humboldt Foundation.]