EEG slow frequency and WISC-R correlates.

On the basis of slow frequency indices obtained from computerized EEG assessments, 36 children were ranked the highest and 23 the lowest in a heterogeneous population of children involved in a brain-behavior assessment program. WISC-R results show the high or excess slow frequency group to have low verbal and normal performance subtest scores, while those with the least slow frequency activity were above normal on verbal and performance scores. Discriminant function analyses of the WISC-R profiles significantly separated the two EEG groupings, with the Information Subtest and Verbal IQ the best discriminating measures. The results suggested that diffuse EEG slow frequency reflected a "maturational lag." Cluster analyses showed that the subtest profile was constant independently of IQ. Other findings indicated that the presence of excessive slow frequency activity was associated with less electrophysiological and psychometric differentiation.