A developmental study of specific spelling disability.

Previous studies have identified a group of individuals with specific problems in spelling, and compared them to a group with problems in reading and spelling. Those who are poor at reading and spelling are thought to have more severe underlying language problems. This study compared the cognitive abilities of three groups of children: one specifically spelling disabled, one spelling and reading disabled, and one control group without reading or spelling problems. The groups were identified at age 14. A five-year retrospective analysis of their performance revealed that both of the disabled groups had been significantly poorer than the controls, not only in spelling but also in reading. Both the disabled groups showed other signs often associated with dyslexia such as poor WISC-R Coding and Digit Span. Analyses of their spelling errors did not reveal the superior phonetic abilities which some other studies have found to differentiate specifically spelling disabled from reading + spelling disabled groups. The specific spelling disabled group did show some evidence of superiority in Verbal IQ subtests. These results are consistent with the idea that specific spelling disability is a residual problem of individuals who, possibly by means of underlying verbal strengths, have managed to compensate for earlier reading difficulties.