Differentiating Between Difficult-to-Remediate and Readily Remediated Poor Readers

Abstract

In this article we discuss research bearing on the traditional use of the IQ-achievement discrepancy to define specific reading disability. We initially review the evidence presented by Rutter and Yule (1975) in support of this practice, and then discuss results from subsequent studies that have questioned the reliability of their findings. We also discuss results from more recent studies demonstrating that the IQ-achievement discrepancy does not reliably distinguish poor from normal readers, whereas language-based measures do reliably distinguish these groups. We highlight results from a study we recently completed, in which it was found that IQ scores did not differentiate between poor readers who were found to be readily remediated and poor readers who were difficult to remediate. In view of the convergent evidence against the use of IQ scores to define specific reading disability, we suggest that the IQ-achievement discrepancy definition of this disorder be discarded.

Educators' Understanding of Dyslexia: A Survey Exploring the Need for Professional Development in the Areas of Prevention and Intervention

“…Findings from a variety of studies indicate that both dyslexic and garden-variety disabled readers demonstrate phonological processing deficits that are not related to IQ test scores, but are common to both groups of readers (Gresham & Vellutino, 2010;Siegel, 1998;Stanovich, 1988;Stanovich & Siegel, 1994;Vellutino et al, 1996). Furthermore, evidence indicated the IQ-discrepancy model did not differentiate between children who could be easily remediated versus those children who were more difficult to remediate (Gresham & Vellutino, 2010;Vellutino et al, 1996;Vellutino et al, 2000;Vellutino et al, 2006). Although the IQ-discrepancy model has not disappeared from the educational landscape and continues to be used in school environments, renunciation of this model by the research community demonstrated a significant change in perspective regarding the identification of children with reading disabilities and encouraged the development of improved methods for identification purposes.…”

“…This model required the demonstration of discrepant scores on IQ and achievement tests in order to diagnose a reading disability and presumed that discrepant readers identified as dyslexic differed significantly from their garden-variety counterparts who lacked discrepant scores due to low IQ scores and demonstrated weaknesses in both decoding and comprehension (Gough & Tunmer, 1986;Lyon, 1995). Application of the IQ-discrepancy model reflected the influence of studies conducted by Rutter and Yule during the 1970s (Fletcher et al, 1994;Gresham & Vellutino, 2010;Vellutino et al, 2000). Rutter and Yule (1975) identified two types of disabled readers:…”

“…Children with specific reading retardation exhibited IQ scores that differed significantly from their achievement scores while children with general reading backwardness demonstrated both low IQ scores and low achievement scores. Rutter and Yule's descriptions provided the foundation upon which the IQ-discrepancy model was constructed, although later research recognized the weakness of that foundation Gresham & Vellutino, 2010;Vellutino, et al, 2000).…”

“…The neurological aspect of reading disabilities was at least recognized in the IDC-10, as was the recognition of the importance of appropriate opportunities for learning. However, the definition in the IDC-10 does not provide significant guidance when attempting to identify students with reading disabilities and also provides criteria (e.g., the IQ-discrepancy model) that have since been rejected by many researchers in the literacy field Gresham & Vellutino, 2010;Lyon, 1995;Stanovich, 1991;Vellutino et al, 1996;Vellutino, et al, 2000). (Lyon, Shaywitz, & Shaywitz, 2003).…”

“…Findings from several studies (Vellutino et al, 1996;Vellutino, Scanlon, & Lyon, 2000;Vellutino et al, 2004;Vellutino, Scanlon, Small, & Fanuele, 2006) indicated that many children are not actually disabled readers, but simply needed adequate instruction in order to be successful. Results from a longitudinal study conducted by Vellutino et al (1996) concluded that intense intervention could significantly reduce the number of children identified as reading disabled.…”