Cognitive Abilities in Families with Reading Disabled Children

Abstract

Psychometric test data were obtained from 125 reading disabled children, their parents and siblings, and the members of 125 matched control families (total N = 1,044). Principal component analysis of eight tests common to all age groups yielded three readily interpretable ability dimensions—reading, spatial/ reasoning, and coding/speed. Reading disabled children obtained significantly lower scores than control children on all three measures; however, the largest difference was for reading. Both siblings and parents of reading disabled children manifested deficits on the reading and coding/speed dimensions. With regard to the reading measure in siblings, a significant interaction between sex and family type indicated that brothers of reading disabled children were more affected than sisters. Sex differences for spatial/reasoning and coding/speed were significant for all three comparisons (reading disabled children versus controls, parents, and siblings). Males obtained higher spatial/reasoning scores than females but lower scores for coding/speed. Results of this study conclusively demonstrate the familial nature of reading disability and provide evidence for the presence of symbolic processing deficits.