Infant word segmentation and childhood vocabulary development: a longitudinal analysis.

Infants begin to segment novel words from speech by 7.5 months, demonstrating an ability to track, encode and retrieve words in the context of larger units. Although it is presumed that word recognition at this stage is a prerequisite to constructing a vocabulary, the continuity between these stages of development has not yet been empirically demonstrated. The goal of the present study is to investigate whether infant word segmentation skills are indeed related to later lexical development. Two word segmentation tasks, varying in complexity, were administered in infancy and related to childhood outcome measures. Outcome measures consisted of age-normed productive vocabulary percentiles and a measure of cognitive development. Results demonstrated a strong degree of association between infant word segmentation abilities at 7 months and productive vocabulary size at 24 months. In addition, outcome groups, as defined by median vocabulary size and growth trajectories at 24 months, showed distinct word segmentation abilities as infants. These findings provide the first prospective evidence supporting the predictive validity of infant word segmentation tasks and suggest that they are indeed associated with mature word knowledge. A video abstract of this article can be viewed at http://www.youtube.com/watch?v=jxzLi5oLZQ8.

Better working memory for non-social targets in infant siblings of children with Autism Spectrum Disorder.

We compared working memory (WM) for the location of social versus non-social targets in infant siblings of children with Autism Spectrum Disorders (sibs-ASD, n = 25) and of typically developing children (sibs-TD, n = 30) at 6.5 and 9 months of age. There was a significant interaction of risk group and target type on WM, in which the sibs-ASD had better WM for non-social targets as compared with controls. There was no group by stimulus interaction on two non-memory measures. The results suggest that the increased competency of sibs-ASD in WM (creating, updating and using transient representations) for non-social stimuli distinguishes them from sibs-TD by 9 months of age. This early emerging strength is discussed as a developmental pathway that may have implications for social attention and learning in children at risk for ASD.

The Social Orienting Continuum and Response Scale (SOC-RS): a dimensional measure for preschool-aged children.

Children with autism show deficits in social referencing, joint attention, orienting to their names, and social smiling as early as the first year of life. The present study describes the development of the Social Orienting Continuum and Response Scale (SOC-RS), a quantitative scale assessing each of these behaviors during the course of video-recorded Autism Diagnostic Observation Schedule (ADOS) sessions. The SOC-RS was shown to be reliable and valid, and when applied to a longitudinal sample of children studied at 2 and 4 years of age, was shown to be sensitive to decreased levels of social referencing, joint attention, orienting to name, and social smiling in autism. The implications of these findings and potential applications of the SOC-RS are discussed.

The first year inventory: retrospective parent responses to a questionnaire designed to identify one-year-olds at risk for autism.

The First Year Inventory (FYI) is a parent questionnaire designed to assess behaviors in 12-month-olds that suggest risk for an eventual diagnosis of autism. We examined the construct validity of the FYI by comparing retrospective responses of parents of preschool children with autism spectrum disorders (ASD; n = 38), other developmental disabilities (DD; n = 15), and typical development (TD; n = 40). Children with ASD were rated at significantly higher risk on the FYI than children with DD or TD. The DD group was at intermediate risk, also significantly higher than the TD group. These retrospective data strengthen the validity of the FYI and have implications for refining the FYI to improve its utility for prospective screening of 12-month-olds.