Do people with autism or Asperger’s score higher on IQ tests?
Written by Martin Silvertant
There is evidence that suggests some people with ASD have higher IQs, while other people with ASD have lower IQs. Furthermore, the documented IQ of individuals with ASD may be lower than in actuality due to issues with IQ test-taking.
A substantial proportion of individuals with ASD suffer from severe to mild intellectual disability. Research shows that of people with ASD, 55% had an intellectual disability (IQ <70) but only 16% had moderate to severe intellectual disability (IQ <50); 28% had an average intelligence (IQ 85–115), and only 3% were of above average intelligence (IQ >115)[1].
That said, the IQ range for ASD has altered over time. Between 1966 to 1998, studies found that about 20% of the people with ASD functioned in the “normal range” of intelligence. By 2014, 50% of people with ASD had average or above-average intelligence (IQ >85), 33% of people with ASD had an intellectual disability, and 23% had borderline IQ scores (71–85). The alteration of IQs in ASD may be a result of including people with milder forms of autism, such as high-functioning autism.
Nevertheless, average to above average IQs and even giftedness are also present in individuals with ASD, though the exact percentage is unclear. It has been found that those carrying genetic variants linked to autism had slightly better test scores on average than those who did not carry the autism genes[2]. Rather, it indicates that autistic individuals with high IQs are actually purer cases of autism without additional difficulties. When compared to neurotypicals social cognition, visual pattern recognition and verbal working memory was poorer in people with ASD. So it seems that although there is a correlation between genetic variants linked to autism and intelligence both on the lower and higher side.
Also, it should be considered that autism can actually undermine one’s ability to take IQ tests and achieve a high score. A different study has found that autism features may vary in relation to intelligence, and thus have different effects on the IQ scores[3]. The study shows that children with autism who have IQs below 85 show cognitive problems similar to those of controls with equivalent IQs, but children with autism who have IQ scores higher than 115 do much worse on cognitive tests than the controls with similar IQs. So it seems the higher the IQ, the greater the discrepancy between measured IQ and potential ability; among children with above-average IQs, those with autism had substantially lower cognitive scores than controls did.
A different study has looked into a potential correlation between autism and high IQ in child prodigies[4]. Three out of the eight prodigies were found to have autism diagnoses, and four out of eight had close relatives with autism (a total of 11 relatives were reported to be on the autism spectrum). However, surprisingly some of these prodigies didn’t have elevated IQs in correlation with their performance; one of them had an IQ of “only” 108. So it seems this study also suggests some remarkable abilities can be found in individuals with autism spectrum disorders, despite not scoring that high on IQ. Although, take this with a pinch of salt, because obviously this study looked into child prodigies, who are not representative of the average person with autism. Child prodigies have an exceptional working memory, which is not directly linked to autism.
What it comes down to is that the results of both IQ and cognitive tests can be unreliable in people with autism.
Martin Silvertant’s answer to Do people with autism or Asperger’s score higher on IQ tests?
Footnotes
[1] IQ in children with autism spectrum disorders: data from the Special Needs and Autism Project (SNAP).
[2] Autism IS linked to being more intelligent, study finds
[3] Autism features may vary with intelligence | Spectrum | Autism Research News
