Purpose: This study investigates the heritability of language, speech, and nonverbal cognitive development of twins at 4 and 6 years of age. Possible confounding effects of twinning and zygosity, evident at 2 years, were investigated among other possible predictors of outcomes. Method: The population-based twin sample included 627 twin pairs and 1…

While little is known about why children make speech errors, it has been hypothesized that cognitive-linguistic factors may underlie phonological speech sound disorders. This study compared the phonological short-term and phonological working memory abilities (using immediate memory tasks) and receptive vocabulary size of 14 monolingual preschool…

Early language ability is a strong predictor of later language and reading outcomes. Whilst young children with home languages that differ from the dominant language spoken in their country of residence may lag behind their peers in literacy and academic achievement, effective supports for young dual-language users may be overlooked in mainstream…

Using a rich sample created from the Longitudinal Survey of Australian Children, we investigate the extent to which the relationship between body size at birth and early childhood cognitive skills is mediated by physical development indicators. Consistent with existing evidence from other countries, we find a significant relationship between body…

Consequences of theory of mind (ToM) development for daily social lives of children are uncertain. Five to 13-year-olds (N = 195) with typical development, autism, or deafness (both native and late signers) took ToM tests and their teachers reported on their social skills for peer interaction (e.g., leadership, group entry). Groups differed in…

Determining the effectiveness of many special education interventions is most difficult because of the practical and ethical limitations associated with assigning participants to a control or non-treated group. Using Longitudinal Study of Australian Children data, this article utilised eight different propensity score analysis methods to determine…

This study aimed to provide evidence regarding the efficacy of an early literacy preparation program, "PreLit", designed to improve the skills of young Australian children. Participants comprised 240 children in eight schools attending their first year of schooling. Children in the four experimental group schools received instruction in…

The internal/external frame of reference (I/E) model and dimensional comparison theory posit paradoxical relations between achievement (ACH) and self-concept (SC) in mathematics (M) and verbal (V) domains; ACH in each domain positively affects SC in the matching domain (e.g., MACH to MSC) but negatively in the nonmatching domain (e.g., MACH to…

Previous studies suggest that individuals with Williams syndrome (WS), a rare genetically based neurodevelopmental disorder, show specific weaknesses in visual attention and response inhibition within the visuospatial domain. Here we examine the extent to which impairments in attentional control extend to the visuomotor domain using a…

Following a biopsychosocial model, the study investigated the role of child factors (gender, IQ), maternal factors (psychological distress, maternal education and vocabulary, maternal distress) and environmental factors (SES) in the relationship between language impairment and behaviour problems in preschool children. Participants were drawn from…