IQ As It Relates to Intellectual and Developmental Disabilities #AtoZChallenge

Hi everyone and welcome to my letter I post in the #AtoZChallenge. Today, I want to write about IQ. IQ, a measure of intelligence, is one of the determining criteria for intellectual disability. So how is it measured in the general population and in people with an intellectual or developmental disability?

The concept of IQ dates back to the 19th century, when early psychologists first started developing tests for measuring intelligence. These were based on the idea that intelligence increases as a child grows up, so they were based on skill sets a child of a certain age should be able to master. IQ was then decided to be intellectual age divided by chronological age multiplied by 100 (to get the idea that a normal IQ is 100). For example, if a child aged five masters the skills of a three-year-old, their IQ was 3 / 5 * 100 = 60.

This is problematic, because among other things it does not allow for testing of adults and does not allow for variation on different skill levels. It was therefore abandoned in favor of a norm-based IQ testing system. Both the Wechsler scales (most commonly used in Europe) and the Stanford-Binet test (which is used more often in the U.S.), are norm-based, with an IQ of 100 being average and standard deviations of 15 (Wechsler) or 16 (Stanford-Binet) determining differences such as intellectual disability and giftedness.

I am familiar only with the Wechsler scales. There is a preschooler, a children’s and an adult version of these. The children’s and adult versions at least contain non-verbal as well as verbal tasks. Until some years ago, these were divided into categories of verbal and performance IQ. I, for one, can only have my verbal IQ tested. This refers to skills such as math, vocabulary, working memory, information (general knowledge questions), etc. The performance/non-verbal tasks include patterns, object recognition (where you see an object with part of it missing and need to identify it), etc. I am pretty sure that, if my performance IQ could ever be tested, it’d be significantly lower than my verbal IQ, as is commonly the case with verbally capable autistics.

On the other hand, nonspeaking or partly verbal autistics often find their intelligence being underestimated because they struggle on verbal IQ tests or cannot take them at all. For this reason, for nonspeaking autistics, a non-verbal IQ test may be more appropriate.

I did honestly find that the adult Wechsler scale was quite difficult even for me, a person with a high level high school and some college education. I honestly doubt those with a moderate intellectual disability will even be able to answer the simplest of questions on it. For example, the first math question was something like: “John had six apples, Peter had two apples, how many apples did the two of them have combined?” Interestingly, the first vocab question was to define “apple”. And no, in Dutch, there is no ambiguity (in case people are thinking “the brand that makes iPhones”). However, the correct answer was “fruit”, which I struggled to come up with, as that’s not a definition, more like a categorization.

20 thoughts on “IQ As It Relates to Intellectual and Developmental Disabilities #AtoZChallenge

  1. My husband is always finding an IQ test online. They are sometimes fun to take. Surprisingly every time I take one, I score close to what I was told as a child that my IQ was. I must have taken the preschool form because I don’t remember ever taking a test, just being told by my parents what my IQ was whenever I misbehaved in a way they thought was unbecoming to my IQ.

    Liked by 1 person

    1. Oh, that’s so interesting! I feel you about being told about your IQ when you misbehaved. I tested within the gifted range (verbal IQ like I sad) as a child even though that’s probably incorrect. That being said, my parents rarely let an opportunity go by to tell me to act my intelligence.

      Liked by 1 person

          1. I don’t think anyone ever labeled me a genius. I am much too scattery to be taken too seriously. One of my professors called me “semi-smart, and another friend called me a space cadet.” So I was never in danger of having my IQ thrown around at random. I don’t think anyone even knows it now – or cares, for that matter. LOL

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            1. That’s good. My skills are all over the place too, but the one time my parents were actually given an IQ score rather than just a general description of how I compared to other children, there was a retest effect so I did much better than I would naturally have done.

              Liked by 1 person

              1. Interesting! All my testing was done before I remember it, LOL. I always did well on tests in school, so much so that my report cards all said underachiever. Apparently that label didn’t bother my parents enough to force me to improve my grades. 🙂

                Liked by 1 person

                1. Oh, lucky you for not being forced to excel at school. I was always forced to go above and beyond, mostly to (unsuccessfully) prove to my special ed teachers that I was capable of being mainstreamed. Which, guess what, requires more than academic ability.

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                  1. As a teacher, I know that so many kids who went above and beyond, had parents working with them constantly on projects, tutoring, etc. My parents weren’t like that. I was on my own for homework, and frankly, I thought and acted like a kid – not too much motivation to go beyond.

                    Liked by 1 person

                    1. That’s good. I wasn’t helped with my homework much either, but I was constantly encouraged to do extra work particularly in elementary school because at the time I was in special education. Once in mainstream high school, my parents weren’t as pushy anymore, thankfully, but they still didn’t help me either.

                      Liked by 2 people

                    2. My brother was also in special education. He did nothing in school until he reached 3rd grade. Then he got a great teacher who took him up to third grade level. By this time, he was 6th grade age. Then we moved across country. They put him into 7th grade – still special ed, but he graduated from elementary and high school with some basic training. He’s pretty well read, a great thinker with a sense of humor, and eventually married a lawyer.

                      Liked by 2 people

        1. This wasn’t an online test I talked about, this was the official Wechsler intelligence test I had done in 2017. I described the examples to explain why someone with an intellectual disability may not be able to have it administered at all.

          Liked by 1 person

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