Children learn the words of their native language(s) from interactions with their caregivers. Although previous research has found that the language children hear during those interactions predicts vocabulary outcomes, few studies have investigated how qualitative features of social interactions work together to affect children's vocabulary…

The predictive ability of early consonant inventory and intentional communication on later expressive language was examined in 36 boys with fragile X syndrome (FXS). Autism symptom severity was included as a potential moderator. Participants were visited in their homes twice over a 6-year period, and mother-child interactions were videotaped,…

Introduction: Children and young adults with Down syndrome can demonstrate increased behavior problems compared to their typically developing peers through childhood and adolescence. Though current tools measure behavior problems in persons with intellectual disabilities, they do not capture all the behavioral problems that can occur in…

This study aimed to investigate the relationships between abilities to initiate and respond to joint attention and symptoms of autism that have, and have not, been theoretically linked to joint attention. Participants were 51 boys and five girls with autistic disorder, aged between 2 years and 6 years 5 months. Measures of joint attention…

Research examining autistic symptoms in Angelman syndrome (AS) is limited. The goal of this study was to further characterize the nature of stereotyped behaviors, social interaction deficits, and developmental disturbances in individuals with AS. Parents of 248 individuals between the ages of 3 and 22 completed a survey of autistic symptomatology…