Examining the double-deficit hypothesis in vowelized-transparent Arabic in a national representative sample of Grades 3 and 4.

We examined the double-deficit hypothesis in Arabic by investigating the reading and cognitive profiles of readers with selective deficits in naming speed, phonological awareness, or both. In a nationally representative sample of 486 children in the third and fourth grades, we identified 171 children with reading difficulties: 20 (12%) were classified as having a phonological deficit, 31 (18%) as having a naming speed deficit, and 41 (24%) as having a double deficit. Differences between the subgroups extended to reading, cognitive, and linguistic processes beyond phonological and naming abilities. Children with a double deficit performed worse than those with a naming speed deficit but similar to those with a phonological deficit. Numerous unconfirmed theories led to an in-depth analysis of the nature of rapid automatized naming and its relation to orthographic processing. Surprisingly, our findings revealed that orthographic processing may be considered a novel and separate core deficit, suggesting a triple deficit in Arabic rather than a double deficit. The findings are discussed in light of the uniqueness and complexity of Arabic orthography and orthographic transparency in the Arabic language.