Purpose: This study investigated the etiology of late language emergence (LLE) in 24-month-old twins, considering possible twinning, zygosity, gender, and heritability effects for vocabulary and grammar phenotypes. Method: A population-based sample of 473 twin pairs participated. Multilevel modeling estimated means and variances of vocabulary and…

Purpose: This study was designed to examine the early usage patterns of multiple grammatical functions of "DO" in children with and without specific language impairment (SLI). Children's use of this plurifunctional form is informative for evaluation of theoretical accounts of the deficit in SLI. Method: Spontaneous uses of multiple functions of…

Purpose: The current study investigated finiteness marking (e.g., he walk "s", he walk "ed") in boys with fragile X syndrome (FXS); the boys were grouped based on receptive vocabulary (i.e., borderline, impaired). Method: Twenty-one boys with the full mutation of fragile X, between the ages of 8 and 16 years participated. The boys completed probes…

Purpose: The present work describes how vocabulary ability as assessed by 3 different forms of the Peabody Picture Vocabulary Test (PPVT; Dunn & Dunn, 1997) can be placed on a common latent metric through item response theory (IRT) modeling, by which valid comparisons of ability between samples or over time can then be made. Method: Responses from…

Purpose: The mean length of children's utterances is a valuable estimate of their early language acquisition. The available normative data lack documentation of language and nonverbal intelligence levels of the samples. This study reports age-referenced mean length of utterance (MLU) data from children with specific language impairment (SLI) and…

Purpose: Clinical grammar markers are needed for children with SLI older than 8 years. This study followed children who were previously studied on sentences with omitted finiteness to determine if affected children continue to perform at low levels and to examine possible predictors of low performance. This is the first longitudinal report of…

Purpose: The aim of this study was to investigate the language outcomes of 7-year-old children with and without a history of late language emergence at 24 months. Method: One hundred twenty-eight children with a history of late language emergence (LLE) at 24 months and 109 children with a history of normal language emergence (NLE) at 24 months…

Purpose: The primary objectives of this study were to determine the prevalence of late language emergence (LLE) and to investigate the predictive status of maternal, family, and child variables. Method: This is a prospective cohort study of 1,766 epidemiologically ascertained 24-month-old singleton children. The framework was an ecological model…

Purpose: Although mean length of utterance (MLU) is a useful benchmark in studies of children with specific language impairment (SLI), some empirical and interpretive issues are unresolved. The authors report on 2 studies examining, respectively, the concurrent validity and temporal stability of MLU equivalency between children with SLI and…

The relationship between children's language acquisition and their nonverbal intelligence has a long tradition of scientific inquiry. Current attention focuses on the use of nonverbal IQ level as an exclusionary criterion in the definition of specific language impairment (SLI). Grammatical tense deficits are known as a clinical marker of SLI, but…

A study investigated the long-term stability of the teacher and parent behavioral ratings of 37 children with specific language impairment. Results indicate diminishment in teacher-reported behavior problems in most areas of socioemotional development from kindergarten to second grade and increasing congruence between teacher and parent ratings.…

Fifty-seven children (ages 5-8) with and without specific language impairment (SLI) participated in judgment and elicitation tasks designed to evaluate their understanding of irregular verb forms. Differences between SLI and control children were observed in their productions and relative levels of sensitivity to infinitive errors in finite…

Two studies investigated the syntactic bootstrapping abilities of 5- and 7-year-old children with specific language impairment and comparison groups matched for equivalent language level or chronological age. Only typically developing 5-year-olds showed evidence of using syntactic clues. However, continued syntactic growth was seen in all…

This study explored the acquisition of regular and irregular past tense in 21 children with specific language impairment. The findings support a morphosyntactic rather than morphophonological learning model, such as the extended optional infinitive model, with regard to the limitations in finiteness marking and for affected children. (Contains…

This longitudinal study evaluated grammatical judgments of "well formedness" of children (N=21) with specific language impairment (SLI). Comparison with two control groups found that children with SLI rejected morphosyntactic errors they didn't commit but accepted errors they were likely to make. Findings support the extended optional infinitive…