Reading Disability Subtypes and the Test of Memory and Learning

For Study 1, 24 readers with dysphonetic dyslexia and 21 with dyseidetic dyslexia, classified by Boder criteria, were compared to 90 control group participants (45 matched for age and 45 for reading level) on the Composite Memory Index (CMI) score from the Test of Memory and Learning (TOMAL). CMI scores were significantly lower for children with dyslexia (p < .0001). Plotting average subtest score profiles for all reader groups revealed auditory sequential memory impairments for both types of readers with dyslexia, and multiple strengths for good readers. Dysphonetic and dyseidetic dyslexia profiles were nearly identical. For Study 2, average linkage cluster analysis was performed using principal components derived from subtests of the TOMAL. Homogeneous clusters of normal readers and children with reading disabilities emerged. Results indicated that qualitatively distinct subtypes of readers with dyslexia exist.