Brief report: concurrent validity of the Leiter-R and KBIT-2 scales of nonverbal intelligence for children with autism and language impairments.

The concurrent validity of the KBIT-2 Nonverbal IQ and Leiter-R Brief IQ was evaluated for two groups of children: those with high functioning autism and those with language impairments without autism. Fifty-three children between the ages of 4 and 13 years of age participated in the study. The correlation between the scales was large (r = .62) and no statistical difference was found between the means. However, large intraindividual differences were found for 11 children who received scores at least 10 points higher on the Leiter-R Brief IQ, 5 of those scored beyond 20 points higher than nonverbal scores on the KBIT-2. Conversely, 11 children scored at least 10 points higher on the KBIT-2 than on the Leiter-R with 4 of those scoring 20 points higher. These findings highlight the importance of using multiple measures when assessing individuals with autism or language disorders.