Learning Disabilities

Introduction

The number of individuals classified with learning disabilities (LD) has increased dramatically over the last twenty years. This is because the classification of LD is based on the context of school learning. Consequently, considerable latitude exists among psychologists in defining LD. This latitude is reflected in social/political issues as well as non-operational definitions of LD (see Swanson, 1989, for a review).

The purpose of this entry is to bring some commonality to the assessment of LD. We address this problem by providing an operational definition of LD that will be useful in diagnostic assessment. Directions for future diagnostic research are also provided.

Definition

Several definitions refer to LD as reflecting a heterogeneous group of individuals with ‘intrinsic’ disorders that are manifested by specific difficulties in the acquisition and use of listening, speaking, reading, writing, reasoning, or mathematical abilities (see Hammill, 1990, for a review). Most definitions assume that learning difficulties in such individuals are (a) not due to inadequate opportunity to learn, general intelligence, or to significant physical or emotional disorders, but to basic disorders in specific psychological processes, (b) these specific psychological processing deficits are a reflection of neurological, constitutional, and/or biological factors, and (c) there is a psychological [Page 554]processing deficit that depresses only a limited aspect of academic or contextually appropriate behaviour.

Thus, to assess individuals with potential LD, efforts are made to determine: (a) normal intelligence, (b) below normal achievement in isolated academic skills, (c) below normal performance in specific psychological processes (i.e. phonological awareness, working memory) and (d) adequate opportunity to learn (documentation that optimal instruction has been presented but deficits in isolated processes remain).

Assessment Issues

Traditionally, the assessment of individuals with LD has been directed towards (1) isolating specific learning problems, (2) establishing a significant discrepancy between IQ and achievement, and (3) demonstrating that responsiveness to instruction varies from those of other handicapping conditions. The literature notes problems in each of these areas (e.g. Aaron, 1997; Fletcher et al., 1994).