Related Experiment Video
Updated: Aug 15, 2026

Decomposing the Variance in Reading Comprehension to Reveal the Unique and Common Effects of Language and Decoding
Published on: October 11, 2018
Cognitive resemblance in reading-disabled twins
1Department of Psychology, University of California, Santa Barbara 93106.
Abstract:
This study examined the cognitive abilities of 60 pairs of reading-disabled twins aged between eight and 18 years (at least one member of each twin pair had been diagnosed as having a reading disability). Principal component analysis of nine cognitive tests yielded three readily interpretable composites of cognitive abilities--reading, symbol-processing speed and sequential memory. Scores on these three cognitive composites were significantly lower for the disabled readers than for normal readers. Individual differences in these cognitive composites within the reading-disabled twin sample were found to be due to genetic differences. Furthermore, deficits in the reading composite for the reading-disabled sample appear to be heritable.
Related Concept Videos
Self-Discrepancy Theory
Language and Cognition
Learning Disabilities
Dyslexia
Dyslexia is a...
Self-Discrepancy and Its Effects
Theory of Attribution II: Kelley's Covariation Theory
Causes of Similarity-Dissimilarity Effect

