Uncoupling of Reading and IQ Over Time: Empirical Evidence for a Definition of Dyslexia

This resource shows the realtionship between reading, IQ and dyslexia. 

Ferrer, E.
Shaywitz, B.A.
Holahan, J.M.
Marchione, K.
Shaywitz, S.E.
Author(s) Organizational Affiliation
University of California, Davis & Yale Center for the Study of Learning, Reading, and Attention
Publication Year
Resource Type
Number of Pages
Target Audience

Developmental dyslexia is defined as an unexpected difficulty in reading in individuals who otherwise possess the intelligence and motivation considered necessary for fluent reading, and who also have had reasonable reading instruction. Identifying factors associated with normative and impaired reading development has implications for diagnosis, intervention, and prevention. The authors show that in typical readers, reading and IQ development are dynamically linked over time. Such mutual interrelationships are not perceptible in dyslexic readers, which suggests that reading and cognition develop more independently in these individuals. To the authors’ knowledge, these findings provide the first empirical demonstration of a coupling between cognition and reading in typical readers and a developmental uncoupling between cognition and reading in dyslexic readers. This uncoupling was the core concept of the initial description of dyslexia and remains the focus of the current definitional model of this learning disability.

What the experts say

This article provides research evidence that describes the longitudinal relationship of reading difficulties/disabilities and cognitive development. The researchers examined testing data on a group of individuals who entered school in 1983 and who were followed from grades 1 through 12. These students fell into three groups. One group was typical readers who began school as good readers and continued to develop their reading competence. A second group, identified as compensated readers, exhibited reading challenges in elementary school, but not in high school. The third group was described as persistently poor readers who demonstrated reading challenges throughout elementary and high school. The researchers found what they call “an uncoupling between IQ and reading”. This means that an individual can demonstrate typical cognitive development but depressed reading achievement. This finding supports the definition of dyslexia as an unexpected discrepancy between reading and cognitive performance. This is a readable research article, which can help adult education professionals better understand the learning profiles of participants who may struggle with reading in ABE and GED classes.

This research supports the need for adult basic education instructors to have a breadth of exposure and knowledge about various types of reading difficulties and disorders, including developmental dyslexia. This research begins to validate the concept of an individual, child or adult, having the ability to learn to read but because of the learning disability, experiencing a disconnect in being able to accomplish the learning tasks in the same manner as those who do not have these disabilities.

Methods the resource used to collect and analyze the data for the research: Analyses presented are from data collected from the Connecticut Longitudinal Study- a sample survey of Connecticut schoolchildren. Three subtests from the WJ (Woodcock & Johnson) were used for composite reading scores: Letter-Word Identification, Word Attack, and Passage Comprehension. To examine interrelations between cognition and reading over time, the authors used dynamic models based on latent difference scores (LDSs).

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