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BackgroundA growing body of research suggests that fine motor abilities are associated with skills in a variety of domains in both typical and atypical development. In this study, we investigated developmental trajectories of fine motor skills between 6 and 24 months in relation to expressive language outcomes at 36 months in infants at high and low familial risk for autism spectrum disorder (ASD).MethodsParticipants included 71 high-risk infants without ASD diagnoses, 30 high-risk infants later diagnosed with ASD, and 69 low-risk infants without ASD diagnoses. As part of a prospective, longitudinal study, fine motor skills were assessed at 6, 12, 18, and 24 months of age and expressive language outcomes at 36 months using the Mullen Scales of Early Learning. Diagnosis of ASD was determined at the infant’s last visit to the lab (18, 24, or 36 months) using the Autism Diagnostic Observation Schedule.ResultsHierarchical linear modeling revealed that high-risk infants who later developed ASD showed significantly slower growth in fine motor skills between 6 and 24 months, compared to their typically developing peers. In contrast to group differences in growth from age 6 months, cross-sectional group differences emerged only in the second year of life. Also, fine motor skills at 6 months predicted expressive language outcomes at 3 years of age.ConclusionsThese results highlight the importance of utilizing longitudinal approaches in measuring early fine motor skills to reveal subtle group differences in infancy between ASD high-risk and low-risk infant populations and to predict their subsequent language outcomes.Electronic supplementary materialThe online version of this article (10.1186/s11689-018-9231-3) contains supplementary material, which is available to authorized users.

There are clear associations between the overall quantity of input children are exposed to and their vocabulary acquisition. However, by uncovering specific features of the input that matter, we can better understand the mechanisms involved in vocabulary learning. We examine whether exposure to wh-questions, a challenging quality of the communicative input, is associated with toddlers' vocabulary and later verbal reasoning skills in a sample of low-income, African-American fathers and their 24-month-old children (n = 41). Dyads were videotaped in free play sessions at home. Videotapes were transcribed and reliably coded for sheer quantity of fathers' input (number of utterances) as well as the number of wh-questions fathers produce. Children's productive vocabulary was measured at 24 months using the McArthur Bates Communicative Development Inventory MCDI (completed by the mothers), and children's verbal reasoning skills were measured 1 year later using the Bayley Scales of Infant Development. Results indicate that the overall quantity of father talk did not relate to children's vocabulary or reasoning skills. However, fathers' use of wh-questions (but not other questions) related to both vocabulary and reasoning outcomes. Children's responses to wh-questions were more frequent and more syntactically complex, measured using the mean length of utterance (MLU), than their responses to other questions. Thus, posing wh-questions to 2-year-olds is a challenging type of input, which elicits a verbal response from the child that likely helps build vocabulary and foster verbal reasoning abilities.