Results provide no support for the IQ-achievement discrepancy model of dyslexia; non-verbal IQ correlated with all Year-1 language measures¶

Claim · All claims
Evidence · 1 study · associational r2 · q2
Currency · newest study 2017 · checked against its sources 2026-10-20 (automated, 1 of 1 entry) · not reviewed by a person

Subclaims¶

q2 i? Deficit groups did not show average IQ with low language skills; instead non-verbal IQ was significantly positively correlated with all Year 1 measures (e.g., PA r = .344). → Ozernov-Palchik 2017

Evidence¶

Ozernov-Palchik 2017¶

Ozernov-Palchik, O., Norton, E. S., Sideridis, G., Beach, S. D., Wolf, M., Gabrieli, J. D. E., & Gaab, N. (2017). Longitudinal stability of pre-reading skill profiles of kindergarten children: Implications for early screening and theories of reading. Developmental Science. https://doi.org/10.1111/desc.12471

q2 · i? · associational · r2

Pearson correlations between the KBIT-2 Matrices measure and Year 1 measures in the full sample; the article prints "Pearson r estimates with PA = .344, p<.001, with LSK = .140, p<.001, with RAN = .226, p<.001, and with NWR = .276".

"In fact, the non-verbal IQ scores were significantly correlated with all Year-1 language measures, indicating a strong coupling between general cognitive abilities and reading."

Discussion¶

Learner Variables¶

• General Cognitive Ability — predictor: learners who differ on it differ in outcomes
• Learning Disabilities and Developmental Differences — predictor: learners who differ on it differ in outcomes

Related Claims¶

• Kindergarten profile membership predicts differentiated 1st-grade reading patterns: the double-deficit group performed worse than all other profiles on nearly all measures — related
• Non-verbal intelligence measures (Raven, WISC Block Design) are non-significant math predictors when well-specified spatial and memory measures are in the model — related
• Age predicts decoding efficiency in children with dyslexia while working memory and perceptual organization covariate effects are non-significant — related
• Cascade models in which IQ mediates the WM-to-achievement path fit comparably to, but not significantly better than, the original correlated models — related
• PA and RAN deficit profiles are over-represented in low-SES schools, while the double-deficit profile distribution is proportional to school SES group size — related
• Latent profile analysis of kindergarten pre-reading measures yields six distinct performance profiles, including PA risk, RAN risk, and double-deficit risk groups — related
• IQ and working memory are reliable predictors of academic achievement at the beginning of school when domain knowledge is not controlled — related
• Crowding effects, pre-cue dependence and set size effects each correlate significantly with reading and spelling measures — related