Impoverished language in early childhood affects the development of complex sentence structure.
Level 3 - non-randomized controlled study
Non-randomized cross-sectional comparative study with typical language exposure control groups.
PubMed 37255282 · doi:10.1111/desc.13416
What was done
Researchers evaluated the comprehension of 12 American Sign Language (ASL) sentence structures using a randomized sentence-to-picture matching task across three groups: deaf adults with severely impoverished language access until age 9 or older (N = 11), deaf native signers with early access (N = 17), and hearing second-language signers with early spoken language access (N = 10). Comprehension performance was evaluated against lexical iconicity, frequency, length of ASL experience, and non-verbal cognitive scores.
What was found
The abstract reports directional findings without numerical values. Deaf signers with impoverished early childhood language access successfully comprehended basic structures (single-verb/single-argument, agreeing verbs, and semantic classifier paths/spatial relations) but struggled with complex structures containing dual lexical arguments or multiple verbs. Both control groups with early language exposure (deaf native and hearing L2 signers) comprehended the full range of 12 sentence structures, independent of lexical iconicity, frequency, length of ASL experience, or non-verbal cognitive performance.
Why it matters
This study provides evidence that early childhood language exposure is critical for the development of complex grammatical syntax, demonstrating that late first-language acquisition leaves enduring deficits in sentence comprehension regardless of total years of signing experience.
Limits
The total sample size is small (N = 38 across three cohorts). The abstract does not provide exact accuracy percentages, effect sizes, or statistical confidence intervals. Language deprivation was determined retrospectively, and unmeasured differences in educational background or environmental factors could not be fully controlled.