NEUROPSYCHOLOGICAL DIFFERENCES AMONG CHILDREN WITH GOOD AND POOR ACADEMIC SKILLS

Two hundred three kindergarten, two hundred eight second grade, and eighty one learning disabled students ages five through eight were examined using four lateralization indexes consisting of difference scores between conceptual (language and visual-motor), motor, sensory-perceptual, and lateral preference variables. The first data analysis used reading ability, sex, and grade as independent variables and the four lateralization indexes as dependent variables for the kindergarten and second grade students in an effort to find out how these groups differed in relative strength of right and left cerebral hemisphere abilities. Good readers had significantly better left hemisphere abilities than poor readers, although a significant reading by sex interaction showed that males had much stronger lateralization differences than females in the high and low reading groups. Females as a whole showed stronger left hemisphere lateralization than males when compared on motor skills and were better readers than males.;The second data analysis matched kindergarten and second grade students to the groups of learning disabled children using academic ability, sex, and age as independent variables and the four lateralization indexes as dependent variables. The learning disabled group showed stronger relative left hemisphere ability than the normal students on the conceptual skills index and females had stronger left hemisphere ability on the motor skills index than males.;The third data analysis used Pearson Product-Moment correlation coefficients to measure the degree of relationship between reading, spelling, and arithmetic scores on the Wide Range Achievement Test and the four lateralization indexes at the kindergarten and second grade levels for normal students. At the kindergarten level only, arithmetic and motor skills had a correlation significantly greater than zero, showing that for younger children right hemisphere skills are more important than left hemisphere abilities in arithmetic mastery. At the second grade level, reading and spelling were significantly related to the conceptual skills index, showing a greater importance of left hemisphere abilities in these areas. When kindergarten and second grade coefficients were compared significant changes in spelling and the conceptual skills index were shown with left hemisphere abilities becoming more important in the performance of older children. The correlation of arithmetic with the motor skills index also showed a shift of importance from right hemisphere abilities to left hemisphere abilities.;The results generally support the idea that stronger dominant left hemisphere lateralization is related to good academic performance. This strong lateralization could be interpreted as supporting the theory that a greater lateralization of abilities in the hemispheres produces more efficient intellectual functioning or it could indicate that ongoing left hemisphere dysfunction interferes with academic proficiency. Females as a whole showed somewhat stronger left hemisphere lateralization than males, corresponding to higher academic achievement, and strong sex differences were found among above and below average readers with left hemisphere ability much more strongly related to good and poor reading in males. Reading, spelling, and arithmetic became more strongly related to left hemisphere ability, when older normal students were compared to younger students.