Differential effects of congenital left and right brain injury on intelligence.

IQ performance was compared in 28 prepubertal children with unilateral left vs. right hemisphere preperinatal injury. Results indicated statistically superior FSIQ and VIQ in the left-lesioned group. Findings were interpreted as consistent with the hypothesis of a left-right maturational gradient, whereby early right hemisphere damage has a more severe effect on overall intellectual functioning than early left injury. Findings also lend support for a greater crowding effect, as seen in the sparing of verbal skills, after early left hemisphere injury.