Beyond reading and spelling: exploring intelligence profiles in individuals with dyslexia through a Cattell-Horn-Carroll theory lens.

Abstract

Background: Dyslexia, a prevalent learning disability, is associated with specific cognitive profiles. This study investigated the cognitive profiles of children and adolescents with dyslexia in Poland utilizing the Cattell-Horn-Carroll (CHC) theory to understand patterns of strengths and weaknesses.

Participants and procedure: The study analyzed intelligence assessment data from 3,458 Polish children and adolescents (age 10-19 years) diagnosed with dyslexia. Data were obtained from a national research panel. Participants underwent comprehensive intelligence assessments using the Stanford-Binet Intelligence Scales, Fifth Edition (SB5). One-sample t-tests were conducted to compare the sample's SB5 scores to population norms.

Results: Participants with dyslexia scored significantly lower than the population average across all 18 SB5 measures (subtests and IQ indices), with effect sizes ranging from small to large. The largest deficits were observed in verbal abilities (knowledge and visual-spatial processing) and specific IQ indices including verbal IQ, general IQ, knowledge IQ, visual-spatial processing IQ, and working memory IQ.

Conclusions: The findings support the applicability of the CHC theory in understanding the cognitive profiles of individuals with dyslexia. The study highlights specific cognitive weaknesses in crystallized intelligence, visual-spatial processing, and working memory. These results challenge the reliance on the pattern of strengths and weaknesses (PSW) model as a primary diagnostic tool and underscore the importance of comprehensive cognitive assessments for individuals with dyslexia. These findings have implications for targeted interventions and a balanced approach to dyslexia diagnosis.