Learning Disabilities Research & Practice

Arguments in support of the conceptual validity of learning disabilities are presented against the background of current definitional problems. The need to differentiate between classification and identification and the importance of a shared attribute definition are stressed. It is argued that a taxonomy of learning disabilities and related achievement problems will clarify and reduce ambiguities and inconsistencies in prevalence and expression of learning disabilities. It is also argued that current problems are related to the confusion of classification and identification, to inadequate operational measures, to an exclusive focus on individuals rather than contextual systems, and to the failure to recognize that classification serves many purposes.

This paper reviews the theoretical issues surrounding a severe discrepancy in the diagnosis of learning disabilities. The theoretical status of discrepancy is first discussed. It is concluded that the discrepancy concept is difficult to validate theoretically and has become too reified and deified. Components of discrepancy, including ability measures, achievement measures, and the notion of expected achievement, are next discussed. Discrepancy, as an ability-achievement difference, is next discussed with respect to uniqueness, experience, reliability, severity, and measurement models. Finally, the relationship between discrepancy and learning disabilities is discussed. It is argued that discrepancy is best linked to underachievement and that a learning disability should be something more than simply underachievement. It is concluded that discrepancy is a necessary but not sufficient criterion in the identification of a learning disability.

Kavale has described several theoretical objections to the model of severe discrepancy in determining the existence of learning disabilities. Although acknowledging the difficulties, this response describes several advantages of discrepancy considerations. Finally, a model that emphasizes the role of the learning disabilities teacher in diagnosing and remediating specific learning disabilities is described.

This paper reviews the current understanding of the statistical and psychometric issues associated with the severe discrepancy definition of learning disabilities used in PL 94-142. Statistical issues involve model specification, selection of variables, error rate control, and multivariate vs. univariate analysis. Psychometric issues involve appropriate use of reliability and validity information and inadequate conceptualization of the discrepancy construct with respect to concurrent, predictive, and construct validity. In conclusion it is proposed that the statistical and psychometric issues should not drive the psychological theory of learning disabilities, and psychologists should regain control of these issues.

This paper reviews the findings regarding the use of severe discrepancy formulas in the identification of learning disabilities by the Work Group on Measurement Issues In the Assessment of Learning Disabilities (Reynolds, 1984-85; Willson & Reynolds, 1984-85). Alternative considerations are then presented that may ultimately prove more beneficial in the identification of learning disabilities

This article reviews the role of development in the concept of discrepancy. Development is first defined generally and then differentiated into five types. Each type is then related to discrepancy and the notion of normal variability. The nature of individual differences is discussed in relation to the use of discrepancy for identifying other handicapping conditions. A discrepancy between ability and achievement is shown to occur within normal development and therefore is not appropriate for defining learning disabilities. It is concluded that discrepancy may be better used within learning disabilities rather than in between distinguishing learning disabilities and other handicapping conditions.

Presence of a severe discrepancy between intellectual ability and academic achievement has typically been accepted as one of the most fundamental criteria used to identify learning disabilities. However, very little consideration has been given to the educational significance of that discrepancy. This paper discusses this topic, with particular emphasis placed on the issues that need to be considered if a severe discrepancy is to have significant educational implications. The article concludes by suggesting that, while much research is necessary before conclusive decisions can be reached regarding the educational significance of a severe discrepancy, in the interim we need to think carefully about these issues.

Choosing among the alternative aptitude-achievement discrepancy models has significant educational implications. Those implications involve the fundamental concepts of learning disabilities (LD), its characteristics in the Identified LD population, approaches to interventions, and the interface between regular and special education. Two discrepancy models meet established though different psychometric standards. Thus, the models are better distinguished by the concepts and outcomes associated with their application. Several of these outcome standards are reviewed: (a) the relationship of aptitude and achievement, (b) numbers of students meeting a discrepancy criterion, (c) validity influences of the achievement measures, (d) influences on the profiles of students with LD, and (e) potential changes In the referral of students. These issues are reviewed to indicate that the choice between two discrepancy models has many implications beyond just operationalizing one component of the LD eligibility model.

This article assumes that the traditional psychometric approach to understanding performance discrepancies in learning disabled (LD) children may not be appropriate, given the dynamic nature of these children's cognitive processes. Three ways cognitive psychology can apply to the study of performance discrepancies are discussed. These applications include (a) explaining the variance in test performance, (b) focusing on competence, and (c) revealing processing discrepancies when the overt preformances of LD and nonlearning disabled (NLD) children are similar. The article concludes that current approaches to understanding performance discrepancies are insensitive to how LD children represent and access knowledge.