Dyslexia and dyscalculia: Two learning disorders with different cognitive profiles

• Published in: Journal of experimental child psychology 2009-07, Vol.103 (3), p.309-324
• Main Authors: Landerl, Karin, Fussenegger, Barbara, Moll, Kristina, Willburger, Edith
• Format: Article
• Language: English
• Subjects: Arithmetic; Awareness; Biological and medical sciences; Child; Child clinical studies; Child psychology; Children; Cognition & reasoning; Cognition Disorders - psychology; Cognitive Ability; Cognitive Processes; Comorbidity; Comparative Analysis; Correlation; Developmental disorders; Disorders of higher nervous function. Focal brain diseases. Central vestibular syndrome and deafness. Brain stem syndromes; Dyscalculia; Dyslexia; Dyslexia - psychology; Female; Humans; Hypothesis Testing; Information processing; Language and communication disorders; Language Tests; Learning Disabilities; Learning disorders; Learning Disorders - psychology; Magnitude comparison; Male; Mathematical Aptitude; Mathematics; Medical sciences; Memory, Short-Term; Mental number line; Nervous system (semeiology, syndromes); Neurological Impairments; Neurology; Neuropsychological Tests; Number module; Numeracy; Phonetics; Phonological Awareness; Phonological deficits; Phonology; Profiles; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; Reaction Time; Reading Difficulties; Semantics; Short Term Memory; Space Perception; Spatial Ability; Speech Perception; Verbal Learning; Visual Perception
• ISSN: 0022-0965; 1096-0457
• DOI: 10.1016/j.jecp.2009.03.006

This study tests the hypothesis that dyslexia and dyscalculia are associated with two largely independent cognitive deficits, namely a phonological deficit in the case of dyslexia and a deficit in the number module in the case of dyscalculia. In four groups of 8- to 10-year-olds (42 control, 21 dyslexic, 20 dyscalculic, and 26 dyslexic/dyscalculic), phonological awareness, phonological and visual–spatial short-term and working memory, naming speed, and basic number processing skills were assessed. A phonological deficit was found for both dyslexic groups, irrespective of additional arithmetic deficits, but not for the dyscalculia-only group. In contrast, deficits in processing of symbolic and nonsymbolic magnitudes were observed in both groups of dyscalculic children, irrespective of additional reading difficulties, but not in the dyslexia-only group. Cognitive deficits in the comorbid dyslexia/dyscalculia group were additive; that is, they resulted from the combination of two learning disorders. These findings suggest that dyslexia and dyscalculia have separable cognitive profiles, namely a phonological deficit in the case of dyslexia and a deficient number module in the case of dyscalculia.