|
Sign In to gain access to subscriptions and/or personal tools.
|
The External Validity of Age- Versus IQ-Discrepancy Definitions of Reading DisabilityLessons From a Twin Study
Bruce F. Pennington
Bruce F. Pennington, PhD, is a professor of psychology at the University of Denver. After graduating magna cum laude in English from Harvard University, he worked as a school-teacher and started an alternative school in the Brookline, Massachusetts, public schools. He earned his PhD in clinical psychology from Duke University in 1977. He has been doing research on children's disorders for over 15 years. He currently holds both a Research Scientist Development Award and a MERIT Award from the National Institutes of Mental Health.
Jeffrey W. Gilger
Jeffrey W. Gilger, PhD, is currently a research scientist at the University of Denver. After earning a master's in school psychology from California State University, Hayward, he then obtained a PhD from the University of California at Santa Barbara, where he specialized in child development and behavioral genetics. Subsequently, he went on to the University of Iowa Medical School for fellowship in psychiatric genetics. He was recently awarded the 1992 Distinguished Young Researcher Award in Cognitive Science by the National Dyslexia Research Foundation.
Richard K. Olson
Richard K. Olson, PhD, is professor of psychology and associate director of the Colorado Learning Disabilities Research Center.
John C. DeFries
John C. DeFries, PhD, is professor of psychology and director of the Institute for Behavioral Genetics, University of Colorado, Boulder. He is also the director of the Colorado Learning Disabilities Research Center and serves as a consulting editor for the Journal of Learning Disabilities. Address: Bruce F. Pennington, University of Denver, Psychology Department, 2155 S. Race St., Denver, CO 80208.
Recent research has raised the question of whether age- and IQ-discrepancy forms of reading disability (RD) are distinguishable in terms of either their underlying linguistic deficit or their response to treatment, thus threatening the external validity of the traditional distinction between specific reading retardation and reading backwardness. The present study pursued the external validity of this distinction in three domains: (a) genetic etiology, (b) sex ratio and clinical correlates, and (c) neuropsychological profiles. Each of these domains was explored in the RD (n=640) and control (n=436) twins participating in the Colorado Reading Project (514 males, 562 females, with an overall mean age of 12.42 years). Little evidence for external validity was found in terms of the clinical correlates of attention deficit-hyperactivity disorder (ADHD), immune disorders, or handedness. Most importantly, there was no evidence of differential genetic etiology of the two phenotypes in this sample, in that deficits in both phenotypes were similarly heritable (h2g=.40 and .46 for age and IQ phenotypes, respectively) and the genetic correlation between them was high (rG=.88 to .96). However, the genetic and neuropsychological profile analyses did suggest that age- and IQ-discrepancy definitions of RD may relate differentially to component reading processes, such as phonological awareness and orthographic coding.
Journal of Learning Disabilities, Vol. 25, No. 9,
562-573 (1992)
DOI: 10.1177/002221949202500904
 CiteULike  Complore  Connotea  Del.icio.us  Digg  Reddit  Technorati  Twitter What's this?
This article has been cited by other articles:
|
|
|
|
 
J. M. Fletcher, C. Denton, and D. J. Francis
Validity of Alternative Approaches for the Identification of Learning Disabilities: Operationalizing Unexpected Underachievement
J Learn Disabil,
December 1, 2005;
38(6):
545 - 552.
[Abstract]
[PDF]
|
|
|
|
|
|
|
J. Liederman, L. Kantrowitz, and K. Flannery
Male Vulnerability to Reading Disability Is Not Likely to Be a Myth: A Call for New Data
J Learn Disabil,
April 1, 2005;
38(2):
109 - 129.
[Abstract]
[PDF]
|
|
|
|
|
|
|
H. W. Catts, T. P. Hogan, and M. E. Fey
Subgrouping Poor Readers on the Basis of Individual Differences in Reading-Related Abilities
J Learn Disabil,
March 1, 2003;
36(2):
151 - 164.
[Abstract]
[PDF]
|
|
|
|
|
|
|
C. Blair and K. G. Scott
Proportion of LD Placements Associated with Low Socioeconomic Status: Evidence for a Gradient?
Journal of Special Education,
May 1, 2002;
36(1):
14 - 22.
[Abstract]
[PDF]
|
|
|
|
|
|
|
W. Van den Broeck
The Misconception of the Regression-Based Discrepancy Operationalization in the Definition and Research of Learning Disabilities
J Learn Disabil,
May 1, 2002;
35(3):
194 - 204.
[Abstract]
[PDF]
|
|
|
|
|
|
|
B. A. Reiter
Reading Disabilities Related to Word Recognition: Underlying Deficits and Diagnostic Approaches
Canadian Journal of School Psychology,
January 1, 2002;
17(1):
65 - 84.
[Abstract]
[PDF]
|
|
|
|
|
|
|
S. Pisecco, D. B. Baker, P. A. Silva, and M. Brooke
Boys with Reading Disabilities and/or ADHD: Distinctions in Early Childhood
J Learn Disabil,
March 1, 2001;
34(2):
98 - 106.
[Abstract]
[PDF]
|
|
|
|
|
|
|
D. L. Lefly and B. F. Pennington
Reliability and Validity of the Adult Reading History Questionnaire
J Learn Disabil,
May 1, 2000;
33(3):
286 - 296.
[Abstract]
[PDF]
|
|
|
|
|
|
|
M. A. Bonafina, J. H. Newcorn, K. E. McKay, V. H. Koda, and J. M. Halperin
ADHD and Reading Disabilities: A Cluster Analytic Approach for Distinguishing Subgroups
J Learn Disabil,
May 1, 2000;
33(3):
297 - 307.
[Abstract]
[PDF]
|
|
|
|
|
|
|
E. G. Willcutt and B. F. Pennington
Comorbidity of Reading Disability and Attention-Deficit/ Hyperactivity Disorder: Differences by Gender and Subtype
J Learn Disabil,
March 1, 2000;
33(2):
179 - 191.
[Abstract]
[PDF]
|
|
|
|
|
|
|
S. J. Wadsworth, R. K. Olson, B. F. Pennington, and J. C. DeFries
Differential Genetic Etiology of Reading Disability as a Function of IQ
J Learn Disabil,
March 1, 2000;
33(2):
192 - 199.
[Abstract]
[PDF]
|
|
|
|
|
|
|
C. H. Silver, H. Deborah-Lynne Pennett, J. L. Black, G. W. Fair, and R. R. Balise
Stability of Arithmetic Disability Subtypes
J Learn Disabil,
March 1, 1999;
32(2):
108 - 119.
[Abstract]
[PDF]
|
|
|
|
|
