The relationship between intelligence and executive function in high functioning children with autism

The literature on Autistic Spectrum Disorder, (ASD) is full of research on the deficits of executive function (EF) in individuals with ASD, where matching ASD participants to typically developing controls is commonly done on the basis of intelligence testing. This study compares a group of high-functioning individuals with ASD (N= 17) to typically developing age matched controls (N=16) on Kaufman’s K-ABC-II subtests of nonverbal intelligence, and compares these results to previous studies of EF: a free search task and a linear size sequencing using the same group of ASD participants. Results showed that the controls significantly outperformed the ASD group on the nonverbal intelligence tests and found significant correlations of the ASD group’s performance on the IQ test to both the linear size sequencing and free search tasks, where in the latter; no such significance was found in the control group. In addition, the IQ subtests triangles, pattern reasoning and hand movements showed significant correlations to one or both EF tests. The study concludes stating that the deficit in the IQ tests of the ASD participants can in part be contributed to the subtests containing elements of executive processes and that indeed EF is an integral part of IQ. This implication is further strengthened by significant correlations of the IQ test to both tasks of executive function. An additional concluding statement questions the validity of the use of IQ as a matching variable when studying EF in the ASD population, due to the confounding effects of EF on IQ