Purpose The mean length of children’s utterances is a valuable estimate of their early language acquisition. The available normative data lacks documentation of language and nonverbal intelligence levels of the samples. This study reports age-referenced MLU data from children with specific language impairment and children without language impairments. Method 306 child participants were drawn from a data archive, ages 2;6–9;0 years, 170 with SLI and 136 control children. 1564 spontaneous language samples were collected, transcribed and analyzed for sample size and MLU in words and morphemes. Means, standard deviations, and effect sizes for group differences are reported for MLUs, along with concurrent language and nonverbal intelligence assessments, per 6-month intervals. Results The results document an age progression in MLU words and morphemes, and a persistent lower level of performance for children with SLI. Conclusions The results support the reliability and validity of MLU as an index of normative language acquisition and a marker of language impairment. The findings can be used for clinical benchmarking of deficits and language intervention outcomes, as well as comparisons across research samples.

A B S T R A C TThe current study examines the syntactic and prosodic characteristics of the maternal speech to two infants between six and ten months. Consistent with previous work, we find infant-directed speech to be characterized by generally short utterances, isolated words and phrases, and large numbers of questions, but longer utterances are also found. Prosodic information provides cues to grammatical units not only at utterance boundaries, but also at utterance-internal clause boundaries. Subject-verb phrase boundaries in questions also show reliable prosodic cues, although those of declaratives do not. Prosodic information may thus play an important role in providing preverbal infants with information about the grammatically relevant word groupings. Furthermore, questions may play an important role in infants' discovery of verb phrases in English.

Speech processing relies heavily on the integration of auditory and visual information, and it has been suggested that the ability to detect correspondence between auditory and visual signals helps to lay the foundation for successful language development. The goal of the present study was to explore whether children with ASD process audio-visual synchrony in ways comparable to their typically developing peers, and the relationship between preference for synchrony and language ability. Results showed that there are differences in attention to audiovisual synchrony between typically developing children and children with ASD. Preference for synchrony was related to the language abilities of children across groups.

Purpose This study was designed to examine the early usage patterns of multiple grammatical functions of DO in children with and without SLI. Children’s use of this plurifunctional form is informative for evaluation of theoretical accounts of the deficit in SLI. Methods Spontaneous uses of multiple functions of DO were analyzed in language samples from 89 children, 37 children with SLI age 5;0–5;6, 37 age-equivalent children, and 15 language-equivalent children, age 2;8–4;10. Proportion correct as well as the types of errors produced were analyzed for each function of DO. Results Children with SLI had significantly lower levels of proportion correct Auxiliary DO use compared to both control groups, with omissions of the DO form as the primary error type. Children with SLI had near-ceiling performance on Lexical DO and Elliptical DO, similar to both control groups. Conclusions Plurifunctionality is not problematic: children acquire each function of DO separately. Grammatical properties of the function, rather than surface properties of the form, dictate whether SLI children will have difficulty using the word. Overall, these results support the Extended Optional Infinitive account of SLI, and the use of difficulty with Auxiliary DO as part of a clinical marker for SLI.

The present case study describes a complexity approach to the treatment of tense and agreement deficits in a child (SC, age 3 years and 11 months, male) with a delay in morphosyntax. We investigate whether it is possible to elicit target treatment structures (auxiliary BE in questions) in a child who does not attempt them spontaneously. Furthermore, we ask whether such elicitation promotes accuracy in target form production and generalization to less complex forms as predicted by complexity accounts. Intervention consisted of a play-based drilled task eliciting the target structure. The intervention was effective in eliciting the intervention target, as SC demonstrated increased production of the target and decreased number of prompts required to elicit the target. SC made moderate gains in the spontaneous use of the proposed generalization structures. This preliminary case study demonstrates that a complexity approach may be feasible for treatment of morphosyntax and provides support for future treatment efficacy studies.