Vocabulary depth, vocabulary breadth, and speechreading as predictors of reading comprehension and inference accuracy in deaf adolescents

The current study examined the contributions of vocabulary breadth, vocabulary depth, and speechreading to reading ability in 37 severely and profoundly deaf adolescents aged 14 to 16 years. Participants completed assessments of nonverbal cognitive ability, vocabulary breadth, vocabulary depth, speechreading, word reading, sentence comprehension, and passage comprehension. Vocabulary depth was the most consistent predictor across all reading outcomes, whereas vocabulary breadth was not significantly associated with any reading measure. Nonverbal cognitive ability, vocabulary depth, and speechreading together accounted for 77% of the variance in word reading accuracy and 86% of the variance in sentence-level comprehension. Vocabulary depth and nonverbal cognitive ability were significant predictors of passage comprehension (explaining 67% of variance), as well as performance on both literal and inferential comprehension questions. These findings underscore the importance of rich and precise word knowledge for reading development and suggest that interventions targeting vocabulary depth may enhance reading comprehension in deaf adolescents.