In autism spectrum disorders, results of cognitive testing inform clinical care, theories of neurodevelopment, and research design. The Wechsler Intelligence Scale for Children and the Stanford-Binet are commonly used in autism spectrum disorder evaluations and scores from these tests have been shown to be highly correlated in typically developing populations. However, they have not been compared in individuals with autism spectrum disorder, whose core symptoms can make testing challenging, potentially compromising test reliability. We used a within-subjects research design to evaluate the convergent validity between the Wechsler Intelligence Scale for Children, 4th ed., and Stanford-Binet, 5th ed., in 40 youth (ages 10-16 years) with autism spectrum disorder. Corresponding intelligence scores were highly correlated (r = 0.78 to 0.88), but full-scale intelligence quotient (IQ) scores (t(38) = -2.27, p = 0.03, d = -0.16) and verbal IQ scores (t(36) = 2.23, p = 0.03; d = 0.19) differed between the two tests. Most participants obtained higher full-scale IQ scores on the Stanford-Binet, 5th ed., compared to Wechsler Intelligence Scale for Children, 4th ed., with 14% scoring more than one standard deviation higher. In contrast, verbal indices were higher on the Wechsler Intelligence Scale for Children, 4th ed., Verbal-nonverbal discrepancy classifications were only consistent for 60% of the sample. Comparisons of IQ test scores in autism spectrum disorder and other special groups are important, as it cannot necessarily be assumed that convergent validity findings in typically developing children and adolescents hold true across all pediatric populations.
Keywords: IQ; Measurement; autism spectrum disorder; cognitive; convergent validity.
© The Author(s) 2014.