Homogeneous subgroupings of learning disability
Specific learning disability in individuals of otherwise normal intelligence has long been a significant problem for educators, parents, and social scientists in general. A quick survey of the literature demonstrates the tremendous amount of research conducted in the field of learning disabilities. Yet, with very few exceptions, the population of learning disabled children has been treated as a relatively homogeneous subgroup of the entire school age population. However, it has become increasingly apparent that there are many subgroups of these children. There is a need to delineate more precisely and objectively, relatively homogeneous subgroups of learning disability. The current investigation attempted to delineate these homogeneous subgroups. In the present study, a group of 100 children between six and thirteen years of age diagnosed as learning disabled were subdivided into four homogeneous subgroupings based on diagnostic test performance using what has been termed a "reiterative sorting procedure". A discriminant analysis demonstrated a correctness of classification ranging from 90.2% to 97.8%. A factor analysis performed on the test score data of these subjects revealed four interpretable factors. Strong evidence for the validity of these procedures was shown as highly similar results were obtained from analysis of a second group of 100 subjects. Homogeneous subgroupings of learning disability were discussed in terms of the modality specific behavioral expression of the specific form of learning disability manifest in each of the four subgroupings. Each of the four interpretable factors was discussed in terms of the more general brain function which underlie the process of learning and the manifestation of a learning disability. In addition, the reiterative sorting procedure was offered as an effective technology for sorting large groups of data into smaller, more homogeneous groupings.