Cognitive and Language Abilities Associated With Reading in Intellectual Disability: A Systematic Review and Meta-Analysis

Cognitive and language abilities influence literacy outcomes in individuals with intellectual disability (ID). The aim of this study was to investigate abilities associated with decoding and reading comprehension in individuals with ID with a systematic review and a correlational meta-analysis. A total of 26 studies with 27 samples and 1,137 participants were included in the meta-analysis. The results showed that reading comprehension was significantly related to decoding ( r = .63), vocabulary ( r = .51), listening comprehension ( r = .43), and IQ ( r = .32). Decoding was significantly related to phonological awareness ( r = .52), phonological short-term memory ( r = .46), rapid automatized naming ( r = −.44), vocabulary ( r = .34), chronological age ( r = .26), IQ ( r = .30), visual short-term memory ( r = .24), and executive-loaded working memory ( r = .32). Limitations connected to unexplained heterogeneity and study quality were found and discussed. This meta-analysis showed that variables identified in studies of typically developing children are relevant for individuals with ID indicating that theories about literacy could reasonably be applied to this population.