The Relationship Between Nonverbal IQ and Executive Dysfunction in Autism Research
Jeffries, Fiona W
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Intelligence plays an important role in investigating executive dysfunction in autism as subjects are often matched or selected on the basis of their level of intelligence. Significant associations between executive function performance and performance on intelligence tests have been found. Hence researchers have begun to question whether intelligence tests are appropriate matching instruments. In an attempt to explore the relationship between executive functions and intelligence test scores in children, the association between scores on a nonverbal intelligence quotient (NVIQ) test and scores on two tasks of executive function were examined. The main aim of the study was to discover whether matching subjects on a NVIQ score might be counterproductive in that the NVIQ test itself picks up on executive function abilities, thus hiding the true nature of executive function deficits. Subjects in the current study completed a NVIQ test. These results were analysed alongside results from two executive function tasks previously completed by the same sample. Results confirmed the hypothesis that NVIQ (not confounded with age) significantly predicted scores from both the executive function tasks, albeit this effect was seen only in autistic children and not in typically developing controls. Some subtests on the NVIQ test had stronger relationships with executive function scores than others, although the results differed slightly between the two executive function tasks. Findings are considered in terms of their implications for research practice and it is recommended that researchers exercise caution when matching or selecting subjects using intelligence test scores. Suggestions for future research are discussed.