Perceptual and Motor Skills, 1992, 74, 77-78.
O Perceptual and Motor Skills 1992
HEMISPHERIC ASYMMETRY A N D RECATEGORIZED WISC-R PATTERNS IN LEARNING-DISABLED A N D NONDISABLED CHILDREN ',' LYNDA G. JOHNSON AND RANDALL W. EVANS Learning Services Corporation Summary.-The relationship between hemispheric processing and recategorized WISC-R patterns (spatial strengths and depressed Acquued Knowledge scores) in 14 learning-disabled and 14 nondisabled boys was examined. A genetic-prenatal hormonal basis appears most plausible.
A plethora of researchers have attempted to understand the bases of learning disabilities. Unfortunately few have attempted to integrate findings from psychometric studies with advances in cognitive psychology and neuropsychology. I n this study a group of 14 learning-disabled boys exhibiting a pattern of elevated Spatial scores and depressed Acquired Knowledge scores on the WISC-R were compared with a group of 14 nondisabled boys on hemispheric processing of verbal stimuli (mean ages 12-0 and 11-3, respectively). All were enrolled in public schools. Fourteen of the 28 were average or above average readers. The other 14 exhibited a significant discrepancy between their intellectual abilities and academic achievement. Consistent with previous research, the learning-disabled group showed less lateralized processing of verbal stimuli (4). O n a task measuring nonverbal processing, however, both groups showed a right hemisphere advantage. These results are inconsistent with previous findings that learning-disabled individuals show bilateral processing of spatial stimuli ( 5 ) . Means and standard deviations on the four information processing tasks are presented in Table 1. Two multiple regression analyses were performed to examine the relationships among reading scores, recategorized Wechsler subtest scores, and hemispheric difference scores. I n the first analysis Wechsler subtest scores and hemispheric difference scores were entered as two sets, with mean reading scores as the criterion variable. Both sets accounted for significant proportions of the variance in reading scores. Hemispheric difference scores d o n e did not account for a significant proportion of the variance in Spatial scores. I t was concluded that a finding of less lateralized processing alone seems 'Address correspondence to L. G. Johnson, Ph.D., Carolina Community Re-entry Program, 707 yorehead Avenue, Durham, NC 27702. A detailed account with tables is on file in Document NAPS-04897. Remit $11.05 lor photocopy or $4.00 for fiche to Microfiche Publications, POB 3513, Grand Central Station, New York, NY 10163.
78
L. G . JOHNSON & R . W. EVANS TABLE 1 MEANSA N D STANDARD DEVIATIONSFORHEMISPHERIC PROCESSING TASKS(ns = 14)
Task
Learning Disabled M
SD
Nonlearning Disabled M
SD
Word Naming Left Hemisphere Right Hemisphere Word Choice Left Hemisphere Right Hemisphere Picture Naming Lefr Hemisphere Right Hemisphere Form Choice Left Hemisphere Right Hemisphere
inadequate to account for either the reading deficits or spatial strengths of the learning-disabled group. Evidence suggests that there may be over-representation of spatial abilities in individuals gifted in areas such as art, architecture, engineering, and athlerics at the expense of language functions. The neurological basis for this is not well understood but has been hypothesized to be a result of prenatal hormonal influences (2). Recent MRI studies have found enlargements in brains of dyslexic children in the splenium of the corpus callosum (1) and aberrant asymmetry in the prefrontal and parietal regions of language- and learning-impaired children (3). Researchers should integrate consistent findings from psychometric and neuroanatomic studies of dyslexic individuals and repeat analyses like the present one, increasing the numbers of subjects as feasible. REFERENCES 1. DUARA,R., KUSCH, A , , GROSS-GLENN, K., BARKER,W., JALLAD,B., PASCAL,S., LOEWENSTEIN, D. A , , SHELDON, J., RABIN,M., LEVIN,B., & LUBS, H. (1991) Neuroanatomic differences between dyslexic and normal readers on magnetic resonance imaging scans. Archives of Neurology, 48, 410-416. 2. G E S C ~ DN., , & GALABLIRDA, A. M. (1987) Cerebral hteralization-biological mechanisms, associations, and pathology. Cambridge, MA: Massachusetts Institute of Technology Press. 3. JERNIGAN, T. L., HESSELINK, J. R., SOWELL,E., & TALLAL,I? A. (1991) Cerebral structure on magnetic resonance imaging in language and learning impaired children. Archives of Neurology, 48, 539-545. 4. WITELSON,S. F. (1976) Sex and the single hemisphere: specialization of the right hemisphere for spatial processing. Science, 193, 425-427. 5. WITELSON,S. F. (1977) Developmental dyslexia: two right hemispheres and none left. Science, 194, 309-311. Accepted January 6, 1992.
O Perceptual and Motor Skills 1992
HEMISPHERIC ASYMMETRY A N D RECATEGORIZED WISC-R PATTERNS IN LEARNING-DISABLED A N D NONDISABLED CHILDREN ',' LYNDA G. JOHNSON AND RANDALL W. EVANS Learning Services Corporation Summary.-The relationship between hemispheric processing and recategorized WISC-R patterns (spatial strengths and depressed Acquued Knowledge scores) in 14 learning-disabled and 14 nondisabled boys was examined. A genetic-prenatal hormonal basis appears most plausible.
A plethora of researchers have attempted to understand the bases of learning disabilities. Unfortunately few have attempted to integrate findings from psychometric studies with advances in cognitive psychology and neuropsychology. I n this study a group of 14 learning-disabled boys exhibiting a pattern of elevated Spatial scores and depressed Acquired Knowledge scores on the WISC-R were compared with a group of 14 nondisabled boys on hemispheric processing of verbal stimuli (mean ages 12-0 and 11-3, respectively). All were enrolled in public schools. Fourteen of the 28 were average or above average readers. The other 14 exhibited a significant discrepancy between their intellectual abilities and academic achievement. Consistent with previous research, the learning-disabled group showed less lateralized processing of verbal stimuli (4). O n a task measuring nonverbal processing, however, both groups showed a right hemisphere advantage. These results are inconsistent with previous findings that learning-disabled individuals show bilateral processing of spatial stimuli ( 5 ) . Means and standard deviations on the four information processing tasks are presented in Table 1. Two multiple regression analyses were performed to examine the relationships among reading scores, recategorized Wechsler subtest scores, and hemispheric difference scores. I n the first analysis Wechsler subtest scores and hemispheric difference scores were entered as two sets, with mean reading scores as the criterion variable. Both sets accounted for significant proportions of the variance in reading scores. Hemispheric difference scores d o n e did not account for a significant proportion of the variance in Spatial scores. I t was concluded that a finding of less lateralized processing alone seems 'Address correspondence to L. G. Johnson, Ph.D., Carolina Community Re-entry Program, 707 yorehead Avenue, Durham, NC 27702. A detailed account with tables is on file in Document NAPS-04897. Remit $11.05 lor photocopy or $4.00 for fiche to Microfiche Publications, POB 3513, Grand Central Station, New York, NY 10163.
78
L. G . JOHNSON & R . W. EVANS TABLE 1 MEANSA N D STANDARD DEVIATIONSFORHEMISPHERIC PROCESSING TASKS(ns = 14)
Task
Learning Disabled M
SD
Nonlearning Disabled M
SD
Word Naming Left Hemisphere Right Hemisphere Word Choice Left Hemisphere Right Hemisphere Picture Naming Lefr Hemisphere Right Hemisphere Form Choice Left Hemisphere Right Hemisphere
inadequate to account for either the reading deficits or spatial strengths of the learning-disabled group. Evidence suggests that there may be over-representation of spatial abilities in individuals gifted in areas such as art, architecture, engineering, and athlerics at the expense of language functions. The neurological basis for this is not well understood but has been hypothesized to be a result of prenatal hormonal influences (2). Recent MRI studies have found enlargements in brains of dyslexic children in the splenium of the corpus callosum (1) and aberrant asymmetry in the prefrontal and parietal regions of language- and learning-impaired children (3). Researchers should integrate consistent findings from psychometric and neuroanatomic studies of dyslexic individuals and repeat analyses like the present one, increasing the numbers of subjects as feasible. REFERENCES 1. DUARA,R., KUSCH, A , , GROSS-GLENN, K., BARKER,W., JALLAD,B., PASCAL,S., LOEWENSTEIN, D. A , , SHELDON, J., RABIN,M., LEVIN,B., & LUBS, H. (1991) Neuroanatomic differences between dyslexic and normal readers on magnetic resonance imaging scans. Archives of Neurology, 48, 410-416. 2. G E S C ~ DN., , & GALABLIRDA, A. M. (1987) Cerebral hteralization-biological mechanisms, associations, and pathology. Cambridge, MA: Massachusetts Institute of Technology Press. 3. JERNIGAN, T. L., HESSELINK, J. R., SOWELL,E., & TALLAL,I? A. (1991) Cerebral structure on magnetic resonance imaging in language and learning impaired children. Archives of Neurology, 48, 539-545. 4. WITELSON,S. F. (1976) Sex and the single hemisphere: specialization of the right hemisphere for spatial processing. Science, 193, 425-427. 5. WITELSON,S. F. (1977) Developmental dyslexia: two right hemispheres and none left. Science, 194, 309-311. Accepted January 6, 1992.
