International Portal of Teacher Education

Source: Review of Educational Research. Vol. 79, Iss. 4; pg. 1362-1390 (December 2009).
(Reviewed by the Portal Team)

This article synthesizes the experimental literature that compares the academic, cognitive, and behavioral performance of adults with reading disabilities to those of average-achieving adult readers.

Three questions directed this synthesis:
1 . What domains of performance (i.e., intellectual, academic, cognitive, vocational, and life adjustment) clearly differentiate adults with RD from their average-reading counterparts?
2. What performance similarities or differences among adults with and without RD are a function of variations in age, ethnicity, and gender?
3. What performance differences emerge in adults with RD when compared to their counterparts as a function of variations in IQ and reading level?

In all, 52 studies met criteria for a meta-analysis, yielding 776 effect sizes (ESs) with an overall a weighted ES of 0.72 (SD = 0.54).

The results revealed that adults with RD varied substantially in ESs from adults without RD on the classification measures (reading comprehension, reading recognition, verbal intelligence).
More importantly, the results on the comparative measures (i.e., those not used as part of the classification criteria) yielded moderate to high weighted ESs. ESs in favor of adults without RD emerged on measures of cognition (naming speed, phonological processing, verbal memory) and achievement (word attack, math, vocabulary, spelling, and writing).
Low to moderate ESs emerged on measures of general intelligence, problem solving/reasoning, visual memory, monitoring or executive processing, perceptual skills, personality, and neuropsychological indices.

Furthermore, an analysis of the influence of age was done to determine whether the magnitude of differences between RD and average-achieving adults persisted across different age levels.
The results of the hierarchical linear modeling clearly indicated that age, as well as gender ratio, were unrelated to the magnitude of ESs when the influence of the classification and comparison categories of dependent measures was partialed out in the analysis. Thus, the results support the notion that reading achievement and cognitive deficits in adults with RD are persistent across age.

Finally, the results indicated that larger ESs emerged for studies with relatively high IQs when compared to studies with IQ and reading scores in the same low range.

There are at least three implications.
1. The authors found support for the notion that verbal IQ and specific cognitive measures are valid components in the assessment of RD.
2. Tentative support was found for the use of cutoff scores in IQ as a valid model for determining RD.
3. The authors found support for the notion that problems in RD extend beyond a phonological core deficit.