Sign language in d/deaf students' spoken/written language development: A research synthesis and meta-analysis of cross-linguistic correlation coefficients

This paper presents the first systematic review and meta-analysis on cross-linguistic correlations between sign language and spoken/written language competences in bilingual d/Deaf learners. A total of 202 effect sizes were identified based on 70 independent samples that appeared in 52 studies from 1981 to 2023 (N = 3570). The effect sizes involved seven sign language correlates (e.g., fingerspelling, phonological awareness [PA], lexico-semantic knowledge) and eight spoken/written language correlates (e.g., PA, lexico-semantic knowledge, word reading, reading comprehension). Estimated mean correlations of 26 cross-linguistic relationships ranged from r = 0.322 (p < 0.001) for sign language PA and reading comprehension to r = 0.645 (p < 0.001) for fingerspelling and word reading. Among other moderators, age/grade (elementary, secondary, vs. university/adult), signer status (native vs. non-native), program type (bilingual vs. Total Communication/SimCom), and task type (passage vs. sentence comprehension) either showed significant moderation effects or resulted in differing size (small, medium vs. large) in the correlation coefficients among subgroups of primary studies. The meta-analytic findings lend support to the legitimate application of linguistic interdependence, common underlying proficiency, cross-linguistic transfer facilitation, and their associated constructs to the educational development of signing/bimodal bilingual learners. The moderator analysis results, in particular, have shed light on the conditioning of linguistic interdependence and transfer and expanded current understandings about the complexity of the issue and its practical implications in bilingual deaf education.