Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)


Medical Sciences


Professor L.S. Siegel


The role of visual-spatial and short-term memory factors in reading and arithmetic disabilities was explored in 30 children with a reading disability: 41 with an arithmetic disability; and 70 who were achieving normally in reading, spelling, and arithmetic. All of the children had a PPVT-R score 80 and/or a WISC-R Block Design score 9. Percentile cut-off scores on the WRAT were used to classify the children into the three achievement or groups. The children were divided into three age groups (7-9, 10-11, 12-14) in order to study possible differences in cognitive performance between each disability group and the normal comparison group as a function of age. Two experimental arithmetic (Mixed Drill, Missing Symbols) and two experimental language tests (McGill Decoding Words and Nonwords), plus 4 visual-spatial tasks (Block Design, Rey-Osterreith CompIex Figure (Copy), Yerkes Blocks, Left-Right Orientation), and 5 short-term memory measures (Rey-Osterreith Complex Figure (Memory), Rey-Davis Form Board, Numerical Square, Digit Span, Phonemic - Confusability Rhyming and Nonrhyming Letters) were, administered to the children. The scores of the reading disabled children, compared to those of the normally achieving children in the same age category differed significantly in all three age groups on the following measures: McGill Decoding Words and Nonwords, Mixed Drill and Missing Symbols, Rey-Osterreith Complex Figure (Copy version), Digit Span, Phonemic - Confusability, and Numerical Square. In addition, the scores of the reading disabled children in the 7-9 age group on the Block Design and Rey-Osterreith (Memory version) tests, and in the 10-11 and 12-14 groups on the Rey-Davis 3-dimensional task, were significantly lower than those of the normally achieving children. There were no differences between the two achievement groups on the Yerkes Blocks and Left-Right Orientation tests. Considering the arithmetic disabled children in the 7-9 and 10-11 age groups, their scores differed significantly from those of the normally achieving children on the Yerkes Blocks test; as did those in the 10-11 and 12-14 age groups on the Block Design, Rey-Osterreith (Copy version), and Phonemic - Confusability (Rhyming letters) tasks. In addition, the groups differed significantly at the 7-9 and 12-14 age levels on the Rey-Osterreith (Memory) and Digit Span tests; and on the Rey-Davis 3-d and Numerical Square tasks at the 12-14 age level. There were no significant differences on the Left-Right Orientation test. The results suggest that while the performance of the reading disabled children in general is essentially normal on some measures of spatial visualization and spatial orientation; it is poor on other tasks measuring language, arithmetic, visual-motor skills, and short-term memory for language stimuli. In addition, only the younger (7-9) reading disabled children appear to have problems involving aspects of visual-spatial abilities (i.e., visual-perceptual, and spatial organization skills), and difficulties in memory for complex visual figures. The results pertaining to the arithmetic disabled children at all three age levels suggest that they have a problem in spatial visualization, and a complex memory difficulty which particularly involves visual materials. The data also point to a problem involving spatial organization and visual-motor skills which is evident after the age of 9. These findings highlight the importance of chronological age and developmental factors in learning disabilities research. They also point to the need to consider both the maturational lag and deficit positions in explaining the complex pattern of cognitive problems in both reading and arithmetic disabilities. In addition, the results indicate the possibility of a predominant involvement of the left cerebral hemisphere in reading disabilities, and a primary role of the right hemisphere in arithmetic disabilities.

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