Profiles of language development in pre-school children: a longitudinal latent class analysis of data from the Early Language in Victoria Study.

BACKGROUND: Pre-school language impairment is common and greatly reduces educational performance. Population attempts to identify children who would benefit from appropriately timed intervention might be improved by greater knowledge about the typical profiles of language development. Specifically, this could be used to help with the early identification of children who will be impaired on school entry. METHODS: This study applied longitudinal latent class analysis to assessments at 8, 12, 24, 36 and 48 months on 1113 children from a population-based study, in order to identify classes exhibiting distinct communicative developmental profiles. RESULTS: Five substantive classes were identified: Typical, i.e. development in the typical range at each age; Precocious (late), i.e. typical development in infancy followed by high probabilities of precocity from 24 months onwards; Impaired (early), i.e. high probabilities of impairment up to 12 months followed by typical language development thereafter; Impaired (late), i.e. typical development in infancy but impairment from 24 months onwards; Precocious (early), i.e. high probabilities of precocity in early life followed by typical language by 48 months. The entropy statistic (0.84) suggested classes were fairly well defined, although there was a non-trivial degree of uncertainty in classification of children. That half of the Impaired (late) class was expected to have typical language at 4 years and 6% of the numerically large Typical class was expected to be impaired at 4 years illustrates this. Characteristics indicative of social advantage were more commonly found in the classes with improving profiles. CONCLUSIONS: Developmental profiles show that some pre-schoolers' language is characterized by periods of accelerated development, slow development and catch-up growth. Given the uncertainty in classifying children into these profiles, use of this knowledge for identifying children who will be impaired on school entry is not straightforward. The findings do, however, indicate greater need for language enrichment programmes among disadvantaged children.

The Early Language in Victoria Study: predicting vocabulary at age one and two years from gesture and object use.

The Macarthur-Bates Communicative Development Inventories (CDI) have been used widely to document early communicative development. The paper reports on a large community sample of 1,447 children recruited from low, middle and high socioeconomic (SES) areas across metropolitan Melbourne, Australia. Regression analyses were conducted to determine the extent to which communicative behaviours reported at 0 ; 8 and 1 ; 0 predicted vocabulary development at 1 ; 0 and 2 ; 0. In support of previous findings with smaller, often less representative samples, gesture and object use at 1 ; 0 were better predictors of 2 ; 0 vocabulary than were gesture and object use at 0 ; 8. At 1 ; 0, children from the lower SES groups were reported to understand more words than children from the higher SES groups, but there were no SES differences for words produced at 1 ; 0 or 2 ; 0. The findings add to our understanding of the variability in the development of early communicative behaviours.

Locative terms and Warlpiri acquisition.

Cognitive complexity and complexity of linguistic structure have been found to influence the order of acquisition of locatives. In Warlpiri, locative terms are nominals and they are used in combination with a locative case marker on the reference object; directional affixes may be added to them. Data from a series of tests of Warlpiri children's comprehension and production of the Warlpiri expressions that may be translated as 'in', 'on', 'under', 'in front of', 'behind' and 'between' indicate that the locative case forms are used first without the more specific locative nominals; young children distinguish an 'up-down' dimension but not 'in', and the reference object influences how the locative term is interpreted; kamparru-pirdangirli ('front-behind') is not one dimension for children aged four to five years; kulkurru 'between' is understood before kamparru 'front' and pirdangirli 'behind'; the use of features on a reference object for orientation develops at around six, but the orientation of the reference object, as well as features on the placed object may affect interpretation.