Vocabulary Breadth and Depth in Adults With Developmental Language Disorder

PURPOSE: Developmental language disorder (DLD) affects approximately 7%-11% of children and often persists into adulthood, contributing to long-term challenges in education, employment, and health. Although vocabulary challenges are well-documented in children with DLD, relatively little is known about how these difficulties manifest in adulthood. The current study examines vocabulary knowledge in adults with DLD along two dimensions: breadth (the number of words for which an individual can retrieve a meaning) and depth (quality of semantic knowledge for known words). METHOD: Vocabulary breadth was assessed using the standardized Peabody Picture Vocabulary Test-Fifth Edition (PPVT-5), while a novel scoring system was developed to evaluate vocabulary depth in a well-documented definition task (Wechsler Abbreviated Scale of Intelligence-Second Edition [WASI-II] Vocabulary subtest). Linear regression analyses were conducted to examine group differences between adults with DLD and peers with typical language (TL). RESULTS: = 57) on both vocabulary breadth and depth. The vocabulary breadth measure (PPVT-5) yielded a numerically larger effect size than did the vocabulary depth measure (WASI-II). CONCLUSION: These findings characterize the long-term development of vocabulary skills in adults with DLD and highlight the importance of considering both vocabulary breadth and depth when assessing language profiles in adulthood.