How IQ Tests Underestimate Autistic Students’ Intelligence

Some types of IQ tests may wrongly label autistic children as having intellectual disabilities, say two Florida researchers. Douglas Carothers of Florida Gulf Coast University and Ronald Taylor of Florida Atlantic University presented their findings at the annual convention for the Council for Exceptional Children. As many as 70 percent of autistic children have also been diagnosed with intellectual disabilities.

But, as Carothers and Taylor point out, many IQ tests rely on children responding verbally. As Carothers says on Ed Week’s On Special Education blog:

…many children with autism don’t respond to verbal stimuli and may speak little themselves, but some psychologists expect them to respond to questions on an IQ test out loud. If asked to create a sequence from a series of pictures in order to test their social skills, “they may be more interested in the pieces than the whole,” Carothers continued.

In fact, the examiner’s manual of one IQ test, the WISC-IV, cautions that “it is important not to attribute low performance on a cognitive test to low intellectual ability when, in fact, it may be attributable to physical, language, or sensory difficulties.”

Carothers also notes that IQ tests administered to autistic children by people who don’t know them can “pose a challenge.” An examiner who does not know a child may be unaware of subtle and idiosyncratic ways that a child communicates; new situations and interacting with yet unknown-people are often especially difficult for autistic individuals. Add the stress and anxiety that a child may feel in finding her or himself in a test situation and the likelihood of her or him not being able to demonstrate her or his abilities is very high.

Carothers and Taylor’s observations, which they will be publishing in a forthcoming paper, really resonate with me. My teenage son Charlie has scored low on all the IQ tests he has taken. He has very limited speaking ability (he talks in phrases of one to five words that usually contain nouns and concrete words — he doesn’t, for instance, express emotions in speech) and reads a few words (single words, not full sentences). At school, he has no classes in subjects like social studies, science, math and language arts: Charlie’s curriculum is entirely centered around skills of daily living and on vocational skills. Since the IQ tests psychologists at clinics and school districts have given him are based mostly on language, we’ve stopped being surprised at him scoring low.

I am obviously biased as I am Charlie’s mother — but, despite all this, it is clear that Charlie is quite intelligent. He has a phenomenal memory for places, voices, people and music. It is impossible to gauge how much he understands of what is said around him but he clearly understands much more language than he can himself say, based on his responses on hearing conversations in his earshot. He arranged the three car keys on the floor in the configuration in the photo above: He has a marked ability to create and see patterns as well as an awareness of shapes that recalls that of autistic artists Jessica Park and Alex Masket.

Some researchers have pressed to have autistic individuals evaluated using other tests such as the Raven’s Progressive Matrices. A 2011 PLoS ONE study found that individuals with Asperger’s Syndrome had much higher IQ scores with this test. The Raven’s Matrices test for reasoning, novel problem-solving abilities, and high-level abstraction by using non-verbal multiple choice questions. As the PLoS ONE study’s authors emphasize, while a “distinctively uneven profile of intelligence is a feature of the autistic spectrum” — such that “autistic spectrum intelligence is atypical” — it is also “genuine, general, and underestimated.”

We haven’t had Charlie take the Raven’ss Matrices and since testing is always stressful for him — he knows full well he is being judged and evaluated — I don’t think that we will in the near future. But he clearly has a sense for the kinds of non-verbal questions about patterns that the Raven’s Matrices focus on. Often my husband Jim and I have wondered if the very large gap between Charlie’s intelligence and his ability to speak and use words — he has not taken to using any augmentative communication devices — is one reason for the difficult behaviors he can have (including self-injurious ones); that he is so frustrated that he can’t say what he is thinking, his feelings and thoughts come out in a very messy way. He is now at a school where the teachers and therapists understand him very well so those difficult moments have lessened, but can still happen at times of change and transition.

According to the On Special Education blog, while psychologists often note that an IQ test does not seem to really convey a child’s intelligence, school staff “are also under pressure from schools to assess students in certain ways.”  I appreciate Carothers’ response:

“Do what you have to do to satisfy your districts and then do with the kids what serves them best.”


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Duane B.
.4 years ago

Thank you for sharing.

Miacid Tempest
Miacid Tempest4 years ago

I do think autism has nothing to do with intelligence and it probably stems from older times when we knew less about the many ways people communicate. I have NDL, which is basically the opposite problem of what your son has but I agree that he very well could frustrated! I'm glad he is in a place where his needs are met now. I learn a lot differently than most so I have suffered very much from the public school system.

Jennifer U.
Jennifer A4 years ago

We can't place everyone into the same category of intelligence. Autistic people may not be too good at communicating but they could have something else that they're really good at like art, science or music.

Grace Adams
Grace Adams4 years ago

I didn't find out that I have Asperger's until I was in my sixties. I was misdiagnosed as schizophrenic in my late teens. I disliked kindergarten. First through sixth was ok. I learned to read the first time I was allowed to open a book to read "a cat and a rat" after a few weeks of reciting "b buh, c cuh" etc. and then got away with spending most of my time in class just reading books. Secondary school was hell because I got so much homework, I was forced to take it home to work on and my mother got into it--insisting on correcting it and making me copy it over with her corrections--which I thought was grossly unfair to my teachers and my classmates who I had to compete with for grades and a major insult to me and it deprived me of a chance to learn how to proofread myself.

Siti R.
Siti R4 years ago

good to know, thanks!

Kathy Perez
Kathy Johnson4 years ago

I knew a boy in school who had "autistic tendencies" and he was one of the smartest and intellectual individuals I have ever known

Decobecq Brigitte
Decobecq B4 years ago


As IQ test are mostly based on writing, reading, speaking, they do not take in account any other form of intelligence.
For exemple, one said that dolphins are intelligent, but how a man could know something about an another intelligence than this one he is considering.
This is the same for autistic persons. Abilities and cleverness have to be considered from a viewpoint.

Jose M. C.
JOSE M. C4 years ago

The word autistic itself means "living within oneself." People with autism have difficulty communicating with the outside world, in spite of the fact that many have normal or even superior intelligence. The short documentary, "Autism is a World," shows a great example of how wide this dichotomy can be (here's a clip:

Stephen Hawking has a physical disability, but thanks to the right technology, he can continue to provide us with the insights of his thoughts. How many great minds have been denied that opportunity - and continue to lack a voice - because those of us blessed with normal communication and understanding have not yet found ways to help them speak?

Nancy Black
Nancy Black4 years ago

IQ scores do not always determine intelligence. An autistic student doesn't communicate verbally and often is not exposed to the same training and information that the average child is. I find it sad that test scores are used to judge children.

Marilyn L.
Marilyn L4 years ago