Linguistic Skills and Text Reading Comprehension in Prelingually Deaf Readers: A Systematic Review

Despite the considerable scientific interest in researching the reading skills of the deaf population, most of these studies focus on reading comprehension (RC) at the word or sentence level. Such reading activates different underlying language processes than text-level reading, which is more akin to real-life reading literacy. The results of 36 studies on different linguistic skills and their correlation/prediction with text RC of deaf readers are reviewed, taking into account age and two language modalities (spoken language [SpL] and sign language [SL]).

The studies were systematized and analyzed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 (Page et al., 2021).

Most reviewed studies (92%) investigated how lexical and phonological skills in SpL relate to RC in deaf people, although there is a lack of studies (33%) investigating the relationship between morphological and syntactic skills in SpL and text-based RC in deaf people. Although results on phonology are quite conflicting, studies of this review consistently confirm that lexical skills are positively related to text RC. Despite only a few published studies on morphological and syntactic skills and RC in deaf readers, the results show strong evidence of their association. This review also provides evidence of a significant cross-modal correlation between SL skills and RC, by showing that in children and adolescents, better phonological skills and receptive vocabulary are associated to better RC, whereas in adults, only studies examining grammatical skills in SL found a significant association with RC in bimodal bilingual deaf readers.

Lexical knowledge appears to be the primary contributor to text RC in deaf readers, whereas phonological effects remain inconclusive. Although morphological and syntactic competencies' impact warrants further investigation, they demonstrate consistent association with RC. There is also clear evidence of a positive cross-modal relationship between SL skills and RC.