Meta-analysis of the nonword reading deficit in specific reading disorder.

A meta-analysis was conducted to investigate whether specific reading disorder (SRD) groups demonstrate a deficit in using phonological recoding strategies. Thirty-four studies were reviewed that had compared the nonword reading performances of SRD groups with reading-level matched (RL) control groups. The average nonword reading difference between groups across the total number of studies was moderate (d = 0.65, N = 2865). Three predictors of the size of group differences in nonword reading ability were identified. Studies that used passage reading tests to match groups for reading level found significantly less evidence for nonword reading deficits than studies that used word-level reading accuracy tests. Secondly, there was a significant positive relationship between group differences in intelligence level (SRD-RL control group) and effect sizes. Finally, group differences in age showed a significant negative association with effect magnitudes. The mean age, reading level and intelligence level of groups did not significantly predict nonword reading outcomes. It was concluded that there was evidence for nonword reading deficits in SRD groups, consistent with the claim that deficient development of phonological recoding strategies is a leading cause of reading difficulties.