Biomedical subjects

K K McGregor

Publications and source records attributed to K K McGregor.

13 recordsLinked to original sources

PubMed2000

Early lexical development in English- and Korean-speaking children: language-general and language-specific patterns.

The present study examined the composition of the early productive vocabulary of eight Korean- and eight English-learning children and the morpho-syntactic, semantic, and pragmatic characteristics of their caregivers' input in order to determine parallels between caregiver input and early lexical development. Vocabulary acquisition was followed using maternal diary and checklists for the Korean-learning children (from a mean age of 1;6 to 1;9) and for the English-learning children (from a mean age of 1;4 to 1;8). Results showed that both Korean-learning and English-learning children acquired significantly more nouns than verbs at the 50-word mark. However, Korean children learned significantly more verbs than did English-learning children. The relative ease with which Korean learners, as compared to English learners, acquired verbs parallels several differences in the linguistic and socio-pragmatic characteristics of the input addressed to them. Korean-speaking caregivers presented more activity-oriented utterances, more verbs, and more salient cues to verbs than did English-speaking caregivers. These data suggest that both general and language-specific factors shape the early lexicon.

Child Language↗

PubMed1998

Object naming at multiple hierarchical levels: a comparison of preschoolers with and without word-finding deficits.

According to the storage hypothesis (Kail & Leonard, 1986), word-finding deficits in young children are not the direct results of deficient retrieval strategies; they are a manifestation of a general delay in language development that affects lexical storage. In the current study, we explored one aspect of lexical storage, the hierarchical organization of the semantic system, in 13 preschoolers with word-finding deficits (WF) and 13 preschoolers with normal language abilities (ND), ranging in age from 3;3 to 6;7. The children named a series of objects at multiple levels of the noun hierarchy in response to contrast questions (e.g. for rose they were asked, 'Is this an animal?' to elicit plant [superordinate]; 'Is this a tree?' to elicit flower [basic]; 'Is this a dandelion?' to elicit rose [subordinate]). Both groups readily named at multiple levels, providing evidence of hierarchical organization of the lexicon. However, there were several differences between WF and ND groups that suggested that WF children did not have enough stored information to discriminate between similar semantic neighbours. We conclude (1) that hierarchical organization of the semantic lexicon is a robust developmental phenomenon, apparent in both ND and WF preschoolers and (2) that the word-finding deficits of preschoolers appear to reflect insufficient depth and breadth of storage elaboration rather than deficits in hierarchical semantic organization.

Child, Preschool↗

PubMed1997

Follow-up study of a right- and a left-hemispherectomized child: implications for localization and impairment of language in children.

Two hemispherectomized girls, one operated on the right, the other on the left, were followed from time of surgery until 9 and 10 years of age and compared with respect to course of language acquisition following surgery. At conclusion of follow-up, receptive and expressive language, phoneme perception and production, and sentence processing of the two hemispherectomized children were compared with those of two control groups of similar age, one developing language normally, the other language-impaired. The left-hemispherectomized child's abilities were similar to those of the language-impaired children; the right-hemispherectomized child's abilities resembled those of the language-normal children. Implications for localization of developmental anomalies in language-impaired children are discussed.

Brain↗

PubMed1997

Trochaic template use in early words and phrases.

The speech of twenty normally developing children whose linguistic development spanned four MLU stages was recorded. The weak syllable productions in their spontaneous and elicited words and phrases were examined. The children demonstrated more frequent use of weak syllables that occurred in trochaic (strong + weak) than iambic (weak + strong) patterns. The constraint on iambs was not absolute; even children in MLU Stage I produced weak syllables in iambs occasionally. Also, it was not a constraint on lexical representations as the same pattern was evinced for word combinations. Weakly stressed articles were omitted significantly more often from noun phrases that were iambic than from those that were trochaic. These data suggest that a pattern of the form strong syllable + optional weak syllable [S(W)] serves as a template for multisyllabic productions, whether mono- or multimorphemic. With increasing MLU, S(W) template use declined and control of timing distinctions between weak and strong syllables became more adult-like. We conclude that the trochee may function as either an optimal representational unit or as an optimal timing unit for early syllable sequences. The trochaic template is invoked when the complexity of an intended utterance exceeds the child's resources for planning and production.

Child Language↗

PubMed1997

The nature of word-finding errors of preschoolers with and without word-finding deficits.

Twelve preschoolers with word-finding deficits (WF) and their age-matched normally developing (ND) peers participated in three tasks requiring word finding: the noun-naming and verb-naming subtests of the Test of Word Finding (TWF-N, TWF-V) and story retelling. The general error profiles of the two subject groups were similar. Semantic errors were always more common than phonological errors and were typically more common than unrelated errors (e.g., "I don't know" responses). The difference in proportions of semantic and phonological substitutions constitutes developmental evidence for lemma and lexeme distinctions as proposed in adult-based models of lexical storage. Furthermore, the predominance of errors that bore semantic relations to their targets produced by both ND and WF groups suggests an early and robust organization of lexical storage into a network of related information. Despite similarities between the two subject groups, the word-finding deficits of the WF group were manifested in two ways. First, compared to the ND group, the WF group demonstrated significantly higher rates of naming errors on all three tasks; second, they demonstrated significantly different proportions of error types on two of the three tasks. Specifically, the WF group produced a lower proportion of related errors on the TWF-V and a lower proportion of semantic errors on the story-retell task. One clinical implication of these findings concerns measurement of treatment outcomes. A reduction in the number of errors as well as a shift in the error profile towards higher proportions of related errors, especially semantic errors, may indicate progress in word-finding development.

Child Language↗

PubMed1996

Effects of priming on the naming accuracy of preschoolers with word-finding deficits.

Eight preschoolers with word-finding (WF) deficits and 16 controls with normal word-finding abilities (8 preschoolers and 8 adults) named 40 pictured objects under primed and unprimed conditions. Each picture could be correctly labeled with a simple noun or a compound (e.g., cane or walking stick). The primed condition involved semantic primes for both the simple and compound targets as well as a partial lexical prime for the compound targets. All participant groups decreased naming errors when given the primes. Two results indicated that the participants made use of the lexical primes. The first was a shift in form of correct responses from simple nouns in the unprimed condition to compound nouns in the primed condition. The second was an increase in errors that incorporated the lexical prime in the primed condition. There were limits to the benefit that the WF group derived from the primes. First, the primes did not enable the WF group to compensate fully for their naming problems. The gap between the error rates of the WF group and the control groups was not reduced in the primed condition. Second, the quality of errors made by the WF group did not improve in response to primes. Compared to the controls, the WF group made proportionately more errors that indicated no access to the target neighborhood (particularly "I don't know" responses) in the unprimed condition. With primes, the controls further reduced their use of these errors, but the WF group did not. When members of the control groups did make errors, they were more likely than the WF children to produce a word substitution that bore a close semantic, visual, or phonological relation to the target in both unprimed and primed conditions. These limitations on the benefit of priming for participants in the WF group suggest deficiencies in size, elaboration, or organization of their lexicons.

Child Language↗

PubMed1994

Subject pronoun and article omissions in the speech of children with specific language impairment: a phonological interpretation.

Children with specific language impairment (SLI) and their MLU-matched normally developing (ND) peers imitated proper nouns, the pronouns he and you, and the article the in subject phrases. Although all of these word types were phonological phrase-initial syllables, the proper nouns received strong stress, but the function words received weak stress. Both groups of children showed significantly more omissions of the function words than the proper nouns. There was no significant difference amongst the imitations of the two pronouns or the article; all were omitted frequently by both groups. This suggests that the status of subject articles and pronouns as weak syllables in the initial position of phonological phrases may in some cases constitute a more important factor than the distinctive grammatical roles they play. A phonological explanation of subject article and pronoun omissions is explored.

Child Language↗

PubMed1994

Use of phonological information in a word-finding treatment for children.

Two children with word-finding deficits characterized largely by semantic substitutions participated in a treatment involving phonological information about target words. The treatment was motivated by models of naming where semantic information and phonological information are stored in independent ordered components. Given such models, it is possible to characterize some semantic word-finding substitutions as well as phonological word-finding substitutions as the result of breakdown at the level of the phonological output representation. The treatment was organized according to a single-subject multiple baseline design across behaviors and subjects. As hypothesized, the phonologically based treatment resulted in reduction not only of occasional phonological word-finding substitutions but also of the large number of semantic word-finding substitutions displayed during baseline and control measures of confrontation naming. In light of these data, the possible source of word-finding breakdowns in these children is explored.

Child, Preschool↗

PubMed1993

A cross-linguistic study of article use by children with specific language impairment.

Children with specific language impairment (SLI) often show limitations in grammatical morphology that exceed their problems in other areas of language. One factor contributing to this difficulty might be the relatively brief durations of many grammatical morphemes. In the present study, this factor was explored by examining the use of articles by a group of French-speaking children with SLI. French differs from other languages studied to date in that the differences in duration between stressed syllables and unstressed syllables, such as articles, are much smaller. The data revealed that French-speaking children with SLI used articles with relatively high percentages equivalent to those seen for a group of normally developing French-speaking children matched according to mean length of utterance. In addition, the percentages seen for the French-speaking children with SLI were substantially higher than those observed for children with SLI who were acquiring Italian and English.

Child↗

PubMed1992

Converging evidence for underlying phonological representation in a child who misarticulates.

The liquid, fricative, and affricate sounds in the phonological system of a single misarticulating child were the focus of converging analyses. These analyses included structured measures of perceptual and productive skills, language sampling, and acoustic analysis of seemingly homophonous forms. The results of perceptual and productive tasks indicated that the child's perception of certain sounds was superior to his productions, but for other sounds, productive skill was superior to perceptual performance. This child's errors of production could be attributed to nonadultlike underlying representations. A two-lexicon model of underlying representation best accounted for the data. The findings led to inferences about the child's underlying perceptual and articulatory knowledge of fricative, affricate, and liquid sounds.

Articulation Disorders↗

PubMed1992

Grammatical morphology and speech perception in children with specific language impairment.

Many English-speaking children with specific language impairment have been found to be especially weak in their use of grammatical morphology. In a separate literature, many children meeting the same subject description have shown significant limitations on tasks involving the perception of rapid acoustic changes. In this study, we attempted to determine whether there were parallels between the grammatical morphological limitations of children with specific language impairment and their performance profiles across several perceptual contrasts. Because most English grammatical morphemes have shorter durations relative to adjacent morphemes in the speech stream, we hypothesized that children with specific language impairment would be especially weak in discriminating speech stimuli whose contrastive portions had shorter durations than the noncontrastive portions. Results from a group of eight children with specific language impairment with documented morphological difficulties confirmed these predictions. Several possible accounts of the observed morphology-perception parallels are offered.

Child↗

PubMed1991

Unusual phonological patterns and their underlying representations: a case study.

An unusual phonological pattern exhibited by a child aged 2;9 is described. The pattern involved the production of word-final strident continuants in words whose adult forms contain these features in initial, rather than final position (e.g. [ops] for soap). The data are interpreted as compatible with models of child phonology that permit direct mapping of features to final position.

Articulation Disorders↗

PubMed1989

Facilitating word-finding skills of language-impaired children.

Two language-impaired children and their controls participated in a preliminary study designed to examine the effects of treatment on word-finding skills. The 2 children participated in activities designed to improve the elaboration and/or retrieval of the training words, whereas their controls received a therapeutic regimen that did not target word-finding skills. Treatment effects were apparent, with the greatest gains associated with activities focusing on both elaboration and retrieval. Although the findings were promising, several procedural details complicated interpretation of the data.

Child↗