WISC-R verbal and performance IQ discrepancy in an unselected cohort: clinical significance and longitudinal stability.

This study examined children from an unselected birth cohort who had Wechsler Intelligence Scale for Children-Revised (WISC-R) verbal and performance IQ discrepancies that placed them beyond the 90th percentile. It was hypothesized that, relative to their cohort peers, these children would be characterized by greater frequency of perinatal difficulties, early childhood neurological abnormalities, health problems of neurological significance, and concussion. Additionally, it was hypothesized that such children would exhibit more behavior problems, lower academic achievement, and poorer motor skills. Generally, the null hypotheses were not rejected by the results. Longitudinal investigation of the stability of the verbal and performance IQ discrepancy revealed that about 23% of discrepant cases were discrepant at two or more ages. Depressed verbal IQ relative to performance IQ was found to be more common than the reverse pattern. Children with performance IQ greater than verbal IQ scored significantly lower than children for whom this pattern was reversed on measures of academic achievement. Results show that cautious interpretation is needed of verbal and performance IQ discrepancy in the general (nonneurological) assessment setting.