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Questions and Answers
Questions and Answers
Question # 8
Is "specific arithmetic disability" (SAD) the same as NLD? Do all persons with NLD exhibit SAD?
Although most persons who exhibit outstanding difficulties with mechanical arithmetic within a context of adequate to superior single-word reading and spelling (i.e., SAD) also exhibit most of the neuropsychological and psychosocial assets and deficits that characterize NLD, SAD and NLD are not equivalent. Within this context, it should be borne in mind that the vast majority of children who exhibit significant difficulties in mechanical arithmetic also exhibit significant difficulties in single-word reading and spelling. Children with BPPD, for example, typically present with significant deficits in all three areas. These children would not be characterized as exhibiting SAD.
There have been a number of studies focusing on SAD, wherein apart from some of the usual exclusionary LD criteria, outstanding relative deficiency in mechanical arithmetic as compared to single-word reading (and, in some studies, spelling) has been the specific defining feature of the group (e.g., Brandys & Rourke, 1991; Davis, Parry, & Lan, 1997; DeLuca, Rourke, & Del Dotto, 1991; Dool, Stelmack, & Rourke, 1993; Fletcher, 1985; Grunau & Low, 1987; Loveland, Fletcher, & Bailey, 1990; Ozols & Rourke, 1988, 1991; Rourke, 1993; Rourke & Conway, 1997; Share, Moffitt, & Silva, 1988; Siegel & Heaven, 1986; Silver, Elder, & DeBolt, 1999; Silver, Pennett, Black, Fair, & Balise, 1999; Stelmack, Rourke, & van der Vlugt, 1995; Strang & Rourke, 1983, 1985; White, Moffitt, & Silva, 1992). Most of these individual investigations and the reviews thereof have compared the performances of children with SAD to those who exhibit other subgroups and subtypes of LD.
An analysis of the results of these studies and reviews, taken together, leads to the conclusion that groups of children with SAD differ from other reasonably well-defined subgroups of children with LD on a variety of neuropsychological, psychophysiological, and psychosocial dimensions. The differences in evidence would be consistent with those expected were the children with SAD to exhibit NLD. That said, it is important to note that there are a number of other defining characteristics of NLD (see Content and Dynamics section and Pelletier, Ahmad, & Rourke, 2001), and one would expect that the results of comparison studies of children who exhibit all of the NLD characteristics would be much more reliable and valid/robust than would those that employ the single criterion for SAD. The same can be said for comparison studies of Verbal IQ-Performance IQ differences as subgroup criteria. Some of these matters are discussed in Rourke, van der Vlugt, and Rourke, 2002.
Conclusions(1) A significant majority--approximately 65%, by our most recent estimate--of children between the ages of 9 and 15 years who present with definite or probable NLD (classified on the basis of neuropsychological assets and deficits) also exhibit SAD (Pelletier et al., 2001).
(2) Groups of children between the ages of 9 and 15 years who exhibit SAD yield evidence of neuropsychological, psychophysiological, and psychosocial dimensions that would be consistent with those expected were these children with SAD to exhibit NLD. Some of these group findings, however, may reflect group patterns heavily influenced by children within the groups who have NLD that "mask" and/or do not represent the patterns of others within the group who exhibit SAD but not NLD.
(3) Approximately 40% of 7- to 8-year-old children who present with definite or probable NLD (classified on the basis of neuropsychological assets and deficits) also exhibit SAD (Drummond, Ahmad, & Rourke, 2005). Although we have conducted some studies in this area (Drummond et al., 2005; Ozols & Rourke, 1988, 1991), the neuropsychological, psychophysiological, and psychosocial dimensions that would be consistent with those expected were these 7- to 8-year-old children with SAD to exhibit NLD have not been extensively investigated.
Brandys, C. F., & Rourke, B. P. (1991). Differential memory capacities in reading- and arithmetic-disabled children. In B. P. Rourke (Ed.), Neuropsychological validation of learning disability subtypes (pp. 73-96). New York: Guilford Press.
Cirino, P. T., Morris, M. K., & Morris, R. D. (2002). Neuropsychological concomitants of calculation skills in college students referred for learning difficulties. Developmental Neuropsychology, 21(2), 201-218.
Collins, D. W., & Rourke, B. P. (2003). Learning-disabled brains: A review of the literature. Journal of Clinical and Experimental Neuropsychology, 25, 1011-1034.
Davis, J. T., Parr, G., & Lan, W. (1997). Differences between learning disability subtypes classified using the revised Woodcock-Johnson Psycho-Educational Battery. Journal of Learning Disabilities, 30, 346-352
DeLuca, J. W., Rourke, B. P., & Del Dotto, J. E. (1991). Subtypes of arithmetic-disabled children: Cognitive and personality dimensions. In B. P. Rourke (Ed.), Neuropsychological validation of learning disability subtypes (pp. 180-219). New York: Guilford Press.
Dool, C. B., Stelmack, R. M., & Rourke, B. P. (1993). Event-related potentials in children with learning disabilities. Journal of Clinical Child Psychology, 22, 387-398.
Drummond, C. R., Ahmad, S. A., & Rourke, B. P. (2005). Rules for the classification of younger children with Nonverbal Learning Disabilities and Basic Phonological Processing Disabilities. Archives of Clinical Neuropsychology, 20, 171-182.
Fletcher, J. M. (1985). External validation of learning disability typologies. In B. P. Rourke (Ed.), Neuropsychology of learning disabilities: Essentials of subtype analysis (pp.187-211). New York: Guilford Press.
Grunau, R. V. E., & Low, M. D. (1987). Cognitive and task-related EEG correlates of arithmetic performance in adolescents. Journal of Clinical and Experimental Neuropsychology, 9, 563-574.
Loveland, K. A., Fletcher, J. M., & Bailey, V. (1990). Nonverbal communication of events in learning-disability subtypes. Journal of Clinical and Experimental Neuropsychology, 12, 433-447.
O'Hearn, K., & Luna, B. (2009). Mathematical skills in Williams syndrome: Insight into the importance of underlying representations. Developmental Disabilities Research Reviews, 15, 11-20.
Ozols, E. J., & Rourke, B. P. (1988). Characteristics of young learning-disabled children classified according to patterns of academic achievement: Auditory-perceptual and visual-perceptual disabilities. Journal of Clinical Child Psychology, 17, 44-52.
Ozols, E. J., & Rourke, B. P. (1991). Classification of young learning-disabled children according to patterns of academic achievement: Validity studies. In B. P. Rourke (Ed.), Neuropsychological validation of learning disability subtypes (pp. 97-123). New York: Guilford Press.
Pelletier, P. M., Ahmad, S. A., & Rourke, B. P. (2001). Classification rules for Basic Phonological Processing Disabilities and Nonverbal Learning Disabilities: Formulation and external validity. Child Neuropsychology, 7, 84-98.
Rourke, B. P. (1993). Arithmetic disabilities, specific and otherwise: A neuropsychological perspective. Journal of Learning Disabiilties, 26, 214-226.
Rourke, B. P., & Conway, J. (1997). Neurological and neuropsychological dimensions of disabilities in arithmetic and mathematics. Journal of Learning Disabilities, 30, 34-46.
Share, D. L., Moffitt, T. E., & Silva, P. A. (1988). Factors associated with arithmetic-and-reading disability and specific arithmetic disability. Journal of Learning Disabilities, 21, 313-320.
Siegel, L. S., & Heaven, R. K. (1986). Categorization of learning disabilities. In S. J. Ceci (Ed.), Handbook of cognitive, social, and neuropsychological aspects of learning disabilities (Vol. 1, pp. 95-121). Hillsdale, NJ: Erlbaum.
Sikora, D. M., Haley, P., Edwards, J. & Butler, R. W. (2002). Tower of London test performance in children with poor arithmetic skills. Developmental Neuropsychology, 21(3), 243-254.
Silver, C. H., Elder, W. G., & DeBolt, A. J. (1999). Social skills self-appraisal of children with specific arithmetic disabilities. Developmental Neuropsychology, 15, 117-126.
Silver, C. H., Pennett, H. D-L., Black, J. L., Fair, G. W., & Balise, R. R. (1999). Stability of arithmetic disability subtypes. Journal of Learning Disabilities, 32, 108-119.
Stelmack, R. M., Rourke, B. P., & van der Vlugt, H. (1995). Intelligence, learning disabilities, and event-related potentials. Developmental Neuropsychology, 11, 445-465.
Strang, J. D. & Rourke, B. P. (1983). Concept-formation/non-verbal reasoning abilities of children who exhibit specific academic problems with arithmetic. Journal of Clinical Child Psychology, 12, 33-39.
Strang, J. D., & Rourke, B. P. (1985). Arithmetic disability subtypes: The neuropsychological significance of specific arithmetic impairment in childhood. In B. P. Rourke (Ed.), Neuropsychology of learning disabilities: Essentials of subtype analysis (pp. 167-183). New York: Guilford Press.
White, J. L., Moffitt, T. E., & Silva, P. A. (1992). Neuropsychological and socio-emotional correlates of specific-arithmetic disability. Archives of Clinical Neuropsychology, 7, 1-16.
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