Can IQ Scores Really Change?

Mary E. McDonald, Ph.D., BCBA
Educate.
Published in
5 min readMay 15, 2021
Photo by Alexis Fauvet on Unsplash

What does it mean to have an IQ? Well, IQ is an intelligence quotient and it is measured by a few specific intelligence tests. The most common tests that you may have heard of are the Stanford Binet and the WISC-R.

So, let’s talk about the numbers for a moment. If you receive a score between 90–110 then you would be considered to have average intelligence. It is possible to have an IQ that is above or below average. Most of the population has an average IQ, that’s why they call it average because it applies to most of us. About 51% of us fall into this category. Then there are those who are above average or gifted or highly gifted and there are those who fall in a below-average category or have an intellectual disability.

You may be wondering, should you complete an IQ test offered on social media or the internet? Well, if you want to do it for fun then sure, but those are not real IQ tests so don’t put too much stock into the results.

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There is an expectation that IQ scores will remain stable over your lifetime. If someone has a score of 100 at age 5, they will have a score of 100 at age 35 (give or take 5 points). What about all that learning that we do? Well, the IQ test doesn’t measure your learning over time it measures a level of intelligence as that typically remains constant over time.

So, is there ever a time when IQ might change? Maybe if you were John Travolta in Phenomenon? But in real life typically no, not unless there was some type of trauma and that would result in a change to your IQ score. However, there is an exception that I wanted to share with you. I have actually seen IQ scores increase dramatically over someone’s lifetime.

Often people have preconceived notions about what it means to have autism. Very often people assume someone who has autism must also have an intellectual disability. The textbooks will say that about 70–80% of people with autism also have an intellectual disability. I do not agree.

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I know many people with autism and I have determined a few things over the years that may lead to this misnomer. Often, people with autism do not do well on intelligence tests. Period. This may be because they have difficulty attending or may have some interfering behavior that can affect their test score. Attending during the testing session can also be an issue. This may lead them to fall into a lower IQ score than expected and it may leave others expecting less from them.

I have actually observed a drastic change in IQ scores in some children with autism. Now how can that be when IQ is meant to be stable over your lifetime? I have worked with students who had an IQ score in the intellectual disability range when they were first tested. Then years later after years of early intensive behavioral intervention (EIBI), I have seen IQ’s increase by 20, 30, or 40 or more points. I had a student Michael who I started working with when he was age 5 and who scored in an intellectual disability category. Then 3 years after the intervention when he was retested he had an IQ in the average range. What does that mean and how can it be? It means that before the intervention Michael may not have been “testable” and once he had the intensive intervention, he was more capable of taking the test… so maybe the IQ didn’t actually change but we just had a more accurate score now. Maybe this child always had an average IQ and we just weren’t able to see it.

Another interesting story is about a student named Rich. Rich was 12 years old and had a diagnosis of autism. He scored in the below-average range of IQ but I felt that it was not an accurate portrayal of his intelligence. He was somewhat verbal but was definitely more advanced in his receptive, non-verbal skills. We decided to try to find his intelligence score in a different way. We used a non-verbal IQ test called the Leiter. This test measures IQ through a number of visual tasks but does not require verbal responses. This student scored in the gifted range on the Leiter. Did his IQ score change overnight or did this test tell us something different about his intelligence?

This leads me to believe that many individuals with autism do not have an intellectual disability at all. It is our flawed testing that doesn’t allow us to see what they are capable of. It is our narrow minds that don’t allow us to see their intelligence and how creative and brilliant they are.

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It is well known that IQ tests alone don’t mean much and looking at adaptive behavior is more important than looking at IQ scores, not just for people with autism, but for all of us, really. But yet, intelligence tests are still used regularly and therefore people with autism are still judged and categorized based on a number. So, if that is the case then I think it’s important that we at least are able to show their real intelligence so that people do not underestimate their abilities.

So, does IQ change over your lifetime? Yes and no depending on how you look at it. Will your IQ change over your lifetime? Probably not, no. But for people with autism, I do believe the sky is the limit.

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Mary E. McDonald, Ph.D., BCBA
Educate.

Professor @HofstraU, Researcher, Author, Autism Specialist, Behavior Analyst, and Speaker https://www.marymcdonald.org