Is Semantics Affected by Missing a Critical Period? Evidence from the Persian Deaf.
Level 4 - case-series / case-control
Matched case-control study comparing deaf individuals with hearing controls.
PubMed 27007472 · doi:10.1007/s10936-016-9421-7
What was done
Ten Iranian deaf individuals who experienced early-life auditory and language deprivation were compared with ten matched hearing controls. Participants completed a five-task assessment evaluating vocabulary, collocations, semantic categorization, semantic features, and proverbs.
What was found
The abstract reports an overall significant difference between the groups, but gives no exact numerical scores, means, or p-values. In task-by-task comparisons, deaf participants showed no significant difference from hearing controls in error counts for vocabulary, collocations, semantic categorization, or semantic features. The only task with a significant performance deficit in deaf participants was proverb comprehension.
Why it matters
This study suggests that core semantic acquisition may be resilient to early language deprivation, whereas higher-order or figurative semantic comprehension (such as proverbs) may remain selectively vulnerable.
Limits
The sample size is extremely small (10 participants per group), raising high risk of false negatives (type II errors) for the tasks showing no significant differences. The abstract provides no quantitative data (no scores, standard deviations, or effect sizes) and omits details about the exact age of language onset, degree of hearing loss, and educational history.