PROJECT SUMMARY Understanding individual differences in language comprehension and use in autism is a top priority of autism research, as acquisition of language early in life is consistently linked with long-term social, academic, and vocational outcomes in individuals on the autism spectrum. However, studying language of infants and young children who will later be diagnosed with autism is difficult due to the challenges of reliably diagnosing autism in the first 3 years of life, when expressive language develops rapidly. Studying infants who are known to be at increased familial likelihood for autism and language disorder (e.g., based on their status as younger siblings of at least one older autistic child) allows researchers to better understand what factors may predict expressive language in infants who are likely to go on to have autism and/or developmental language disorder. Recent work focused on this population has investigated what caregiver factors influence language development, as caregivers are infants’ primary communication partners and help to scaffold language development by providing linguistic input and facilitating contingent transactions. One such factor is caregiver stress, as caregivers of autistic children report experiencing high levels of stress. In previous work, PI Markfeld found preliminary support for a model whereby perceived, parenting-related stress was indirectly associated with expressive language in toddlerhood via caregiver linguistic input in the home environment in a sample of infants at increased likelihood for autism. The current project will extend the applicant’s prior work in multiple ways. Aim 1 will expand the characterization and measurement of caregiver stress by collecting a measure of stressful life experiences (i.e., objective stressors) in infants at increased familial likelihood for autism. Aim 2 will examine associations between perceived and objective caregiver stress, caregiver linguistic input, and child language outcomes later into childhood (i.e., at age 3 years) in infants at increased familial likelihood for autism. Aim 3 will assess whether this model of how caregiver stress influences child language outcomes may generalize to a larger sample of infants recruited from the general population. It is hypothesized that caregivers of infants at high likelihood for autism will report higher levels of perceived and objective stress relative to caregivers of infants at lower likelihood for autism, but that the conceptual model whereby caregiver stress influences child expressive language via caregiver linguistic input will hold for all caregivers and infants. The comprehensive training plan will advance PI Markfeld’s skills in measurement of caregiver stress and child language, characterization of autism and language disorders, and application of advanced approaches to statistical analyses. If the hypotheses are borne out, this work has the potential to pinpoint novel targets for early interve...