Intelligence (the kind that’s measured on an IQ test) is one kind of human ability. Its importance sometimes gets overinflated, but other times, it seems to get framed as a negative thing. So, how much does intelligence actually matter?
Intelligence and IQ tests
There are all kinds of different human abilities. The psychological construct of intelligence is one kind of ability that’s measured by intelligence quotient (IQ) tests. There’s more detail in a previous post I did on IQ, but according to David Wechsler, who developed the Wechsler Adult Intelligence Scale (WAIS), intelligence is “the global capacity of a person to act purposefully, to think rationally, and to deal effectively with his environment” (as quoted in Wikipedia).
The WAIS, currently in its 4th edition (WAIS-IV), has four subscales:
- Verbal comprehension
- Perceptual reasoning
- Working memory
- Processing speed
It’s scored on a bell curve rather than the raw score you get on a test. It’s normed so that the median score is 100, and 68% of people fall within a range of 100 plus or minus 15 (statistically, one standard deviation).
The concept of emotional intelligence has also been proposed, but from what I’ve read, it hasn’t been as clearly established that it’s a single distinct thing rather than a mishmash of other things. For example, some aspects of what’s captured under the emotional intelligence umbrella may relate to levels of different personality traits like extraversion and neuroticism.
Crystallized vs. fluid intelligence
Psychologist Raymond Cattell formulated the Gf-Gc theory of intelligence. He believed that intelligence (G) came from the coordination of fluid intelligence (Gf) and crystallized intelligence (Gc). Fluid intelligence is the general, untaught ability to understand relationships between elements of an abstract problem, and then use that to solve the problem. Crystallized intelligence comes from knowledge accumulated through experience, and it’s more specific in terms of its usefulness for particular kinds of problems.
Both fluid and crystallized intelligence increase through childhood. In early adulthood, Gf (including processing speed) starts to decline, while Gc stays the same or even increases. Gc can be influenced by experience, but also by factors like interest and motivation.
In a paper on the relationship between general knowledge and intelligence, the researchers concluded that general knowledge is a crystallized ability that comes from applying fluid intelligence over time. However, while intelligence was a factor in people’s level of knowledge, it wasn’t the only one. Personality factors, like higher levels of openness to experience and lower levels of neuroticism and extraversion, were also associated with higher levels of general knowledge, so having a high level of general knowledge doesn’t necessarily mean that someone is highly intelligent.
What intelligence means for school & work
IQ is a strong predictor of early academic success, but it becomes less relevant in higher levels of education. This may relate to the fact that people who’ve made it into higher education are likely to have had a higher IQ to begin with. It may also have to do with crystallized intelligence starting to play a bigger role at that stage of the game.
In terms of job success, the relevance of IQ depends on how complex the job is and the level of intellectual/reasoning demands.
Routine IQ testing
I don’t actually have an idea how widespread routine IQ testing in schools is. It wasn’t a thing when I was going to school.
I haven’t done any reading on whether there are good reasons for routine testing, but it doesn’t strike me as something that would be particularly useful. Intelligence can be a helpful ability to have, but you can’t magic it in or out of existence, so if schools know a kid’s IQ, what are they doing with that information? Unless they’re using it in some way to support all kids to do better, I’m not sure how it’s helping anyone to have those scores.
Aside from that, there are various reasons why an IQ test score may not accurately reflect an individual’s intelligence. Let’s say someone who speaks a particular nonstandard English dialect takes the WAIS-IV IQ test. Scores are based on group norms, and the normative data for a given test is probably based on standard dialect speakers. That test taker’s score on the verbal comprehension scale may not end up representing their actual abilities, because the scoring is making an apples to oranges comparison.
IQ and Health
IQ is correlated with health outcomes and longevity, and this seems to relate to the ability to make use of available information and resources in order to address health-related issues and make decisions about health-related behaviours. Socioeconomic status plays a major role in health, but even within a given socioeconomic group, health differences are observed between individuals of higher and lower intelligence.
However, IQ may also have negative associations with certain health conditions. A study of Mensa members (who are at or above the 98th percentile on IQ tests) found higher than average rates of allergies, asthma, autoimmune conditions, mood disorders, ADHD, and autism spectrum disorder. The researchers proposed a theory to account for this that they described as hyper brain/hyper body.
While research results have been somewhat mixed, childhood intelligence doesn’t appear to play a big role in the risk for dementia in older age. Lifestyle and environmental factors appear to be much more important. It’s possible that higher baseline intelligence might initially mask the early stages of cognitive decline.
The bigger picture
Setting aside the potential flaws of IQ tests, whether someone has high or low intelligence in the IQ sense can give you some information about certain things they may or may not be good at, but it doesn’t tell you whether someone is a good person, what their other abilities may or may not be, or what their personality traits are.
Having high intelligence doesn’t make someone an arrogant ass who’s useless with people; those are distinct elements that can sometimes be present in the same person, but not necessarily. Having low intelligence doesn’t make someone a useless human; there are all kinds of tasks for which other abilities are far more important, and intelligence has no bearing on whether those other abilities are or are not present. Intelligence is just one of the many pieces that make up the bigger picture of an individual.
What are your thoughts on intelligence, what it means, and what it matters for?
- Chamorro-Premuzic, T. (2007). Personality and individual differences. Blackwell Publishing.
- Chamorro-Premuzic, T., Furnham, A., & Ackerman, P. L. (2006). Ability and personality correlates of general knowledge. Personality and Individual Differences, 41(3), 419-429.
- Ghisletta, P., & Lecerf, T. (2018). Crystallized and fluid intelligence. Oxford Bibliographies.
- Karpinski, R. I., Kolb, A. M. K., Tetreault, N. A., & Borowski, T. B. (2018). High intelligence: A risk factor for psychological and physiological overexcitabilities. Intelligence, 66, 8-23.
- Rodriguez, F. S., & Lachmann, T. (2020). Systematic review on the impact of intelligence on cognitive decline and dementia risk. Frontiers in Psychiatry, 11, 658.
24 thoughts on “How Much Does Intelligence Matter?”
Fascinating! I learned a lot from reading this, thanks Ashley for sharing!
This a topic I’m doing some research into at the moment related to personality traits. There is a correlation with openness but like you say it doesn’t necessarily mean because you are one you are both. Something else that’s interesting is the negative correlation found in some cases between intelligence and conscientiousness. It seems those who struggled more at school had to work much harder in order to keep up. Often these individuals are the ones that outpace everyone else late in life. Like you say, just because you are less intelligent doesn’t necessarily mean you are less able. It might even make you more so longer term. Fascinating post – thank you for sharing Ashely. 🙏
That doesn’t surprise me that people who were harder-working would eventually do better than people who were intelligent but coasted earlier on.
We didn’t have IQ testing when I was at school either. I vaguely remember doing an online IQ test years ago, probably during my psych degree, and I scored lower than a 10 year old. I’m too apprehensive to do it again now! There are different types of intelligence like you say and now that my memory is shite, I’m starting to realise that a big part of what’s considered intelligence relies on a half decent memory. You know, the people that can answer all the questions on a TV quiz show or come up with unusual facts and figures they picked up years ago. I’m just glad I did my degree when my memory wasn’t too bad, because there were hundreds of names and dates to memorize! x
My memory is crap now too. I had to do a lot of memorizing for school too, and there’s no way I could manage that now.
I never took an official IQ test, but other tests that correlate to it put me in a very high range (I’m in Mensa and 999, which is beyond Mensa). What does that mean? It means I’m good at taking tests and playing games. It does not translate into career or relationship success. My brainiac friends are a mixed group… some doctors some lawyers some Target workers some unemployed. Many have been single for years, unable to connect with The One (like me). Some are in happy marriages. So there you go! 😂
That’s quite the mixed bag!
Such an interesting post that is so well-researched and well-written, Ashley. What strikes me about IQ tests in schools which they didn’t do when I was young nor do I think they do them now, is that kids that are praised for being smart often get frustrated more easily than kids that are praised for their efforts. So in at least way, it might be effective not to know how “smart” one is until we’ve built our system for how to deal with adversity.
Great post! What role do you think IQ has played in your life?
I like that idea of kids not finding out about how “smart” they are until they’ve developed ways to deal with adversity.
I had an IQ test don’t in grade 3 or so because my parents were trying to push for me to get more gifted services from the school. Looking back at the report from that test as an adult was interesting, because some of the things it said about what I’d be good and how’d I learn best were totally wrong. But I did always like learning new thing, and my parents were very supportive of that.
I think the whole concept of intelligence is flawed. Many here in the Western world associate intelligence with the brain. Most people know nothing about their bodies. We separate the brain from the body when we instead should unite them. Is a person with an IQ of 130 but does not take care of their body intelligent? I think not.
A person who can memorize something is considered intelligent. But in reality, you only have a good memory. And people can never be only rational because there is always a feeling involved in everything you say and do. Are you intelligent if you choose something that hurts you because of rational reasoning? I think not.
I think intelligence is about finding new solutions and going beyond what’s already known. Everything else is just about being book smart and having a good memory (in a nutshell).
I would say that intellectual capacity and the quality of behavioural choices that people make are two distinct things. People’s behavioural choices may be of greater importance than their intellectual capacity, but intelligence as a psychological construct is still defined in terms of the latter rather than the former.
This is really fascinating – does the quality of behavioural choices fall under a defined category? (I suppose it could technically just be Social Science/Psychology, but was hoping for a narrower term)…
I don’t think it would be a single thing because there are multiple ways to evaluate behaviours. Are they values-congruent? Adaptive or maladaptive? Selfish or altruistic? Moral or immoral? Beneficial or harmful to self or others?
Great post as always.
I read a neat summary that said that testing IQ measures how well you score on IQ tests just as testing your chemistry knowledge measures how well you do on chemistry tests.
I value intelligence very deeply, although more than I would like. Intelligence was disproportionately praised by many adults around me growing up, sometimes at the expense/neglect of other positive qualities – not healthy. I hope I round these views out by placing value on emotional intelligence and being a not-a-jerk-human.
Ultimately I believe it’s as meaningful in society (& life) as someone’s physical appearance – it can be powerful and influential, but shouldn’t define a person.
I agree, no single characteristic should define a person. And I think for most people, being well-rounded and having a variety of different skills/abilities is more important than being especially strong in a single area.
Spoiler alert – this is just my personal belief and has not been verified by science to my knowledge.
If it bothers you, just ignore it….. What’s most relevant to me about IQ and IQ testing is that I believe your “score” can change based on how much trauma and impact to the brain you have had because of your mental illness. I believe at one time my IQ was quite high (think I took an IQ test online) but later as my bipolar progressed I believe I lost some of this functionality. I believe that having and living with a mental illness may impact your IQ. The good news is with the loss of cognitive function, it may be that your/our emotional intelligence has developed or progressed as a response to years of managing pain or hardship. I think in the scheme of things I would think emotional intelligence is more important in life than cognitive functioning or IQ.
I agree, mental illness can definitely impair cognitive function. And yeah, emotional intelligence is probably relevant for a lot more areas of life than IQ is.
What are your thoughts on intelligence, what it means, and what it matters for?
After foster care the three of us were tested for IQ (by the standards they had in 1970ish). All three of us had ‘higher than average’ IQs, but one of us topped out at ‘genius’ level (not me). I never thought anything about it until I worked with some cognitively challenged individuals in a care home. I didn’t judge them on being “stupid” or anything, I just noticed the difference in behavior, speech and action compared to myself. Later I worked a job when I was 20 or so, where there were a number of very smart (not the same as intelligent. I get that) people. One was a woman who was working on her 3rd or 4th Master’s degree. Obviously of high intelligence. She was also the one of the stupidest persons I’ve ever met. She had no common sense, she couldn’t spell nor write legibly, she was entitled (parents must have mucho rich) and I came to dislike her intensely because, to me, she was a waste of space and resources. I bet she never held a full time job and was still a student at 64 (not that there’s anything wrong with that). There was another woman, who most thought was stupid as dirt, but who was very intelligent and very smart too. She had quit nursing school to take care of her aging mother, and along the way became morbidly obese. But she was wise and a treasure/pleasure to know. Common sense out the wazoo. Selfless, which the first woman was not.
I’ve never thought of intelligence in the same way before because I doubt (unless it’s overt like those cognitively challenged folks I worked with) anyone can make a snap judgement on intelligence. It doesn’t ‘show” (well I guess the overly entitled show it off if it’s to their advantage). My parents were both (IMO) highly intelligent folks, with my Pops probably having a very high IQ. Their circumstances as adults did not reflect that they had much because they both worked blue collar jobs for low pay. A sibling of mine holds with the fact that they were both “fairly low IQ”. I saw absolute red. My mother was a writer and taught me the value of the English language, she was an original “Grammar and Spelling” cop before such existed. My father overcame so many obstacles to even be educated at all (his parents thought he was ‘slow’ because he’d had polio and had aftereffects neurologically) They treated him like a retard (a word they would throw around easily – it was the times they lived in but they (IMO) were pretty damned ‘slow’ themselves or really really backward (like hicks from the sticks – no offense to any hicks that read this). He got no breaks for teaching himself to be fluent in the Spanish language, to read, to fight to go to school and get his high school diploma.
Er, maybe IQ is a kind of hot button topic for me. Sorry to ramble all over your comments!
It’s sad that it used to be so common (and still is far too common) for parents to put down their kids like your dad’s parents did to him. Why people think that’s an effective way to raise children is beyond me.
I suppose I’d say, “up to a point”. Because intelligent isn’t necessarily prevention against stupid thinking. This piece (https://www.cracked.com/article_20789_6-shocking-studies-that-prove-science-totally-broken.html) is a funny take on all the issues in science because brilliant scientists are also just as the rest of us to bias for dumb reasons like a nonsensical graph, even though these are the people who ought to know better. Also, although there is often correlation, I think there is a difference between “educated” and “intelligent”. And finally, switching gears entirely to something much sadder, intelligence also isn’t a guarantee to happiness and fulfillment – I still remember reading about this child prodigy who committed suicide (https://www.cbsnews.com/news/child-prodigy-14-commits-suicide/). I guess my takeaway is that focusing on better critical thinking skills and on one’s mental health are important, arguably more so, than looking only at natural intelligence.
In its attempts to be funny, the Cracked article seems to have compromised on accuracy. From the way they described the walnuts/diabetes study, they clearly didn’t read the actual paper.
I agree re. educated and intelligent being different things, and intelligence definitely doesn’t prevent mental health issues.
Yeah, Cracked is a humor site not a news one. I picked it more because I could remember where I found the reference to the part about scientists not understanding math or statistics. They’re memorable but not authoritative.
I know there are different types of intelligence, like emotional intelligence and spacial intelligence etc.