EXAMINATION OF INTELLIGENCE MEASURES IN CHILDREN AND ADULTS WITH HIGH-FUNCTIONING AUTISM

Background: Studies of intelligence in individuals with autism have yielded inconsistent results.  Some studies have indicated that individuals with autism can be characterized by VIQObjectives: To investigate IQ measures of the WISC-III/WAIS-III and the Raven’s in relatively more able children and adults with high-functioning autism (HFA).

Methods: The age appropriate Wechsler IQ measures and the Raven’s were collected on 75 children (37 HFA and 38 TD; 8–15 years; mean 11 years) and 91 adults (49 HFA and 42 TD; 16–46 years; mean 26 years).  Autism diagnosis was attained through the ADOS, ADI, and clinical impression.  All participants attained Full Scale IQ’s>70.

Results:   There was no significant difference noted in mean WISC-III and Raven’s percentile scores of HFA children.  However, HFA adults and TD children and adults performed significantly better on the Wechsler assessments than the Raven’s.  TD children and adults displayed similar results between Wechsler Full Scale IQ and Raven’s percentiles, reflecting a stable pattern of development.  HFA participants did not display such similarities between the performances on the two tests.

Conclusions:   The WISC-III and Raven’s are both appropriate measures of intelligence in more able HFA children, yielding similar results. However, as a group, the HFA received lower scores on the Raven’s than on the WAIS-III. The Raven’s did not match results of the Wechsler IQ tests for this more able population. Level of verbal ability may be a factor in these results, with the possibility of inverse results in a less verbal population.