Longitudinal Pathways of Sign Language Development: Tracking Growth and Intervention Outcomes in Deaf Children

About This Grant

Project Summary Deaf children remain at elevated risk for persistent language delays with downstream impacts on literacy and health, even with newborn hearing screening and early intervention. Most signing deaf children move through early grades without consistent discourse-focused sign language intervention. This project will establish the first prospective, multi-site longitudinal cohort of signing deaf children followed systematically under Strategic and Interactive Signing Instruction (SISI), an intervention that develops sign language discourse and then guides translation into written English. This focus is motivated by large-scale longitudinal spoken-language research showing that discourse is a distinct dimension that uniquely predicts later literacy above and beyond vocabulary and grammar; the present study extends this principle in sign language. Approximately 500 children (ages 4-10; PreK-Grade 3) will be tracked for four years across 20 programs for the deaf. The study has three aims: (1) model growth trajectories in sign language development across ages 4-10; (2) test whether growth in sign language predicts growth in written language; and (3) identify child- and intervention-level moderators (e.g., language background, additional disabilities, dosage and fidelity) that accelerate or constrain growth. Children will contribute language samples twice annually in narrative, informational, and persuasive discourses, scored with the Sign Language Complexity Assessment (SLCA) and a parallel writing assessment. SISI fidelity will be monitored three times annually via video-recorded sessions scored with the SISI Fidelity Tool. Growth will be estimated with state-of-the-art longitudinal models. By establishing discourse-based benchmarks for expected growth, clarifying bilingual pathways, and identifying modifiable factors that shape outcomes, the study will enable earlier, more effective intervention, reducing the effects of language deprivation, and improving literacy and health.