Date of Award


Publication Type

Doctoral Thesis

Degree Name





Psychology, Physiological.




With the recognition that learning disability is a heterogeneous class of disorders a number of attempts have been made to identify homogeneous 'subtypes' of children with academic learning disorders. Objective multivariate techniques have been used to classify samples of learning-disabled children into more homogeneous subtypes by constructing profiles of test scores to represent the abilities and deficits exhibited by each subject, and using the classification algorithm to group together subjects with similar profiles. Research using these techniques has shown that a high proportion of children with learning disabilities can be classified reliably into subtypes. In previous classification studies, variables have been selected on rational and empirical grounds to represent the abilities relevant for academic success. The purposes of the present study were to: (1) identify the abilities measured by a large battery of neuropsychological tests using R-type factor analysis; (2) attempt to establish the criterion validity of the factors identified in that analysis; and (3) attempt to classify, with Q-type factor analysis, groups of learning-disabled children into homogeneous subtypes using variables selected to represent each of the abilities identified in the R-type factor analysis. A total of 558 children who had been referred for the assessment of learning disorders were assigned to three groups on the basis of age (7 to 8, 9 to 10, and 11 to 12 years) and studied separately. An R-type factor analysis of the test battery revealed ten factors in each group. The three factor solutions were highly similar although the definition of the factors was more distinct in the two oldest groups. Stepwise linear regression analyses showed that academic achievement scores could be predicted with approximately equal accuracy with either factor scores or the raw scores of the factor-representative variables. The Q-type factor analyses resulted in the classification of between 67 and 77 percent of the subjects in each group. There were four subtypes in the 7-8 year-old group, five subtypes in the 9-10 year-old group, and seven subtypes in the 11-12 year-old group. A number of subtypes were very similar to those identified by other studies; in particular, subtypes characterized by linguistic impairment, visual-spatial and perceptual ability impairment, and impairment of motor ability were found.Dept. of Psychology. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1982 .G384. Source: Dissertation Abstracts International, Volume: 43-07, Section: B, page: 2382. Thesis (Ph.D.)--University of Windsor (Canada), 1982.