Joseph K. Torgesen, Florida State University
Learning Disabilities Summit: Building a Foundation for the Future White Papers
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The term learning disabilities is associated both with a social-political-educational movement and with a field of scientific research and study. Changes to common diagnostic practices as guided by federal regulations will have foreseeable and unforeseeable effects in both areas. As a social-political-educational movement, the field is associated with teacher training programs, parent and professional organizations, legal requirements for educational and workplace accommodations, status as a "handicapping condition," public and private school programs, etc. As a field of scientific inquiry, it is associated with research funding programs, professional identities of scientists, scientific journals and publications, research conventions and questions, etc. Changing the diagnostic criteria for learning disabilities in the manner suggested in this paper will have major impact in some of these areas and little impact in others. It is beyond the scope of this paper (to say nothing of the ability and knowledge of its writer) to give full consideration to all potential effects of a change such as the one proposed here. Nevertheless, a few of the more obvious consequences will be briefly discussed.
One of the most obvious consequences of a change in classification procedures such as the one being recommended here is a change in the characteristics of children being identified for special educational services under learning disabilities regulations. The group identified by these new procedures will be much more heterogeneous with regard to general intelligence. Further, many children currently served as learning disabled might not be served because the absolute level of their academic performance problem may not be sufficiently severe. In current practice, it is the size of the discrepancy between general intelligence and academic skill, rather than the absolute level of academic skill, that leads to a diagnosis of learning disability. Many children with average to above-average general intelligence are served as learning disabled because of the discrepancy between their level of reading skill and their level of general ability, even though the absolute level of their reading abilities is substantially higher than other children who show less of a discrepancy between IQ and reading level. If a criterion involving actual reading level were substituted for the currently used discrepancy criteria, it is obvious that many children with mild reading problems (but large discrepancies) would no longer be served as reading disabled (unless service delivery capacity was considerably expanded over present limits). It is also likely that the ethnic composition and socioeconomic status of children identified as having learning disabilities would shift more strongly toward minorities and lower socioeconomic status groups, because these groups tend to have fewer of the specific types of pre-school language experiences that support the growth of phonological awareness and other pre-academic skills (Whitehurst & Lonigan, 1998).
One of the most widely accepted conventions about learning disabilities is that they involve "unexpected" academic underachievement. The poor academic performance of these children is not expected given their general level of learning ability (as measured by IQ tests), adequate learning opportunities, and reasonable motivation for learning. The trouble with this concept in practice, at least for the development of reading skills, is that standard IQ measures are not equally predictive of all aspects of reading growth. Standard IQ measures are not good independent predictors of early word reading growth (Stanovich, Cunningham & Feeman, 1984; Torgesen et al., 1999), but they are good predictors of individual differences in reading comprehension (Stanovich et al., 1984) once word reading ability has been acquired. IQ measures are good predictors of reading comprehension scores in older children because IQ scores are heavily influenced by level of vocabulary and verbal skills, and this kind of knowledge is also required in reading comprehension. If IQ measures contained a more thorough assessment of phonological abilities and knowledge, they would also be very predictive of growth in early word reading skill. Thus, while general IQ (and particularly verbal IQ) does not lead to clear expectations for growth in early word reading ability, it does justify clear expectations for the ultimate level of reading comprehension that we may expect from individual children. Children with broad verbal and language comprehension abilities far below average cannot be expected to comprehend written material at average levels even if they can decipher all the words in print accurately.
Ultimately, our educational response to children, as well as our system of accommodation to their learning disability, will need to recognize a far greater range of individual differences than it currently does. For example, it is clear that a child with high levels of domain-related knowledge and verbal ability who cannot decipher words fluently should have this reading disability accommodated on tests in which the object is to demonstrate mastery and understanding of a given subject area. However, is there an appropriate accommodation for a child who can decipher the words accurately, but who does not have the domain-related knowledge and broad verbal ability that is required for good performance on the test? The problem, in terms of thinking through the implications of the presently proposed classification scheme, is that both of these students would probably be classified as learning disabled. The example suggests that the concept of accommodations for learning disabilities would need to be more finely developed and clearly articulated than it often is at present.
Another potential consequence of changing the classification criteria for learning disabilities to a system that does not explicitly contain discrepancy criteria is that it might lose its identity as a focus for political action and educational funding. As scientifically flawed and unfair as current discrepancy criteria are, they at least attempt to make a distinction between learning difficulties resulting from specific, constitutionally based processing weaknesses and learning difficulties that are the result of many other causes such as lack of motivation, lack of home support, or low general learning ability. Any classification procedure that does away with the discrepancy idea runs the risk of destroying the concept of learning disabilities in the minds of politicians and educators. The point being made in this paper is that it is not currently feasible to accurately identify children whose learning difficulty is the sole result of an intrinsically based processing disability, and we should not try to do so using invalid discrepancy-based procedures. By publicly acknowledging the problem in moving to a classification criteria that involves neither direct assessment of intrinsic processing weaknesses nor use of discrepancy criteria, we do run the risk of weakening the base for political and social action on behalf of children with developmental learning disabilities.
In contrast to the potential consequences for learning disabilities as a political-social-educational movement, which do involve some serious risks, the change to more encompassing and inclusive criteria for classification of learning disabilities should have mostly positive consequences for the field as an area of scientific inquiry. Perhaps the most positive consequence is that it will underline the heterogeneity of children with learning disabilities in a way that will promote more careful specification of sample characteristics in research as they relate to the questions being asked.
It has long been recognized that researchers should not use school-defined samples of children with learning disabilities as the focus of research, for such samples are simply too heterogeneous to be the basis for coherent theory development (Senf, 1986; Stanovich, 1993; Torgesen, 1993). Since the study of learning disabilities is essentially the study of individual differences in learning and performance, samples should always be carefully selected in relationship to the particular question being addressed in the research. For example, if one wants to determine if weaknesses in a given ability or processing skill can cause a learning difficulty independently from levels of other important abilities (such as verbal or nonverbal intelligence, vocabulary, syntactic skill, general knowledge, etc.) then samples of learning disabled and nondisabled children should be carefully equated on the abilities being controlled. Without such methods, it is arguable that we may never have discovered the unique contributions of word-level reading problems or phonological processes to developmental dyslexia (reading disability), because lower IQ children so frequently also have problems in broad verbal ability and language comprehension (Torgesen, 1989). If the goal is to develop a theory of math disabilities, then only children with a specified type of math disability should be used in the research--and it would also be important to ask how levels of other abilities (such as general intelligence) affect the expression of the disability.
The major threat to the field of learning disabilities as an area of scientific inquiry would involve a potential loss of focused identity if research articles never contained the term learning disabilities but only mentioned topics like "problems with math fact retrieval in children of average intelligence," "difficulties in expressive language in young children with adequate receptive skills," or "factors involved in handwriting difficulties in young children." If a more inclusive definition of learning disabilities applied in the public schools created a loss of cohesion among researchers studying these children, this might make it more difficult to focus public attention on learning disabilities as an area for research funding. It might also create such diversity of focus in professional societies that the synergistic effects found in groups that gather to discuss common interests would be diluted.
Changing procedures for the classification of children with learning disabilities in the manner suggested in this paper would have several clear consequences for the field of learning disabilities as an educational-social-political movement. First, the children identified for learning disabilities services in the school would become more heterogeneous with regard to level of general intelligence. This would require a more differentiated approach to the provision of accommodations than is presently the case, in which children often can receive accommodations simply because of their status as learning disabled. Second, children identified as at risk for learning disabilities on the basis of their performance on process/outcome measures would also be more likely to come from minority ethnic groups and homes of lower socioeconomic status. This would occur simply because children from these kinds of pre-school environments often enter school less well prepared on the critical markers, or predictors for various learning outcomes. Finally, unless service delivery capacity were substantially increased, many children now receiving learning disabilities services would no longer receive them. For example, a child with mild reading difficulties that are significantly discrepant from IQ can qualify for learning disabilities services under current IQ-discrepancy procedures. However, if absolute level of process/outcome scores or reading scores were used to identify children as reading disabled, the same child might not qualify because his or her scores would not be low enough. In order to serve all children who do not have another primary disability but whose learning difficulties in specific academic areas were severe enough to interfere with their ability to accomplish grade level work, there is no question that special instructional capacity for children with learning disabilities would need to be expanded.
The changes to classification procedures recommended in this paper might also impact the scientific study of learning disabilities, but these effects would probably be less severe or threatening than those to the education and politics of learning disabilities. Potentially, the changes could positively affect the scientific study of learning disabilities by forcing investigators to more carefully define their samples, and to select them in more principled ways. The major negative impact might arise from a loss of identity for the field as it divided into separate groups, each focusing on different kinds of learning difficulties.
Funding for NRCLD is provided by the U.S. Department of Education, Office of Special
Education Programs. Award No. H324U010004. Opinions expressed herein are those of the National
Research Center on Learning Disabilities and do not necessarily represent the position of the U.S.
Department of Education.
© 2007 National Research Center on Learning Disabilities
Last Updated: November 19, 2007
Contact: nrcld@ku.edu