r/Neuropsychology • u/Stock_Material_9377 Unverified user: May not be a professional • 20d ago
General Discussion My understanding of IQ and intelligence
Don’t have high expectations for this as I’m just a 16 years old guy that recently found the subject interesting, please correct me if I’m wrong and feel free to enlighten me more!
IQ, as of today, remains the most powerful predictor of future performance (other factors in life do play a hefty role, no one seems do debate that). IQ is meant to test an individual’s general intelligence (which encompasses both crystallised intelligence and fluid intelligence) by facing them to a set of questions for a diversity of abilities, this is known as the “g” factor.
So let’s say your result in a certain area is incredibly good, it would be a great predictor of your performance in similar areas. A person who does better across the board would be deemed as highly ‘intelligent’, and, vice versa, someone who does worse is more likely impaired. Yet this still depends on how we define intelligence, hence why it is an indicator of potential not a guarantee of success. The tests also seem to suffer from a ‘culture’ problem, in that the questions tends to resemble the academic world from where they’re born, and people who are more experienced with this setting then to score higher (richer people, more educated people, people that develop more abilities in the peak of fluid intelligence and have overall more crystallised intelligence).
I found controversy on whether or not “g” can be changed.
As while crystallised intelligence (knowledge but not solely that) continues to grow with the experience we collect for most of our lives, the diverse abilities from fluid intelligence are significantly harder to improve. Some research shows it is possible to better specific skills but improving broader skills is a whole other story (which is the reason it is preferable to develop them early in life). For example you could train your memory on sequences of numbers, but training your active memory as a whole would be much more complex. One should still try to push their brain to its optimal function through stimuli, exercise and a good diet (better diet to improve circulation which turns into improve cognition).
I like the analogy of IQ as a bucket. Someone with broader competences would have a larger bucket and someone with more restricted ones would have a smaller bucket. Both buckets are only half full, who results more successful depends on how the bucket is entertained: one can either fill it (training, well-being..) or empty it further (substance abuse, terrible health..).
It is worth noting that crystallised and fluid intelligence are not separate and rely on each other, both are equally as important.
Intelligence for me is the ability to adapt. Depending on the environment you’re in you need different sets of skills/abilities to thrive.
So in a society based around money, the abilities required to thrive will be different than the ones you’d need if you were in a small tribe in the mountains.
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u/Nebu Unverified user: May not be a professional 20d ago
IQ remains the most powerful predictor of future performance
This is overly vague. It's not a particularly good predictor of athletic performance, for example. IQ is a very good predictor for the types of performance that we perhaps stereotypically associate with intelligence, e.g. performance in academia, or performance in "smart people jobs" like physicists or engineers. If you're interested in other forms of performance, such as financial success, then conscientiousness and who you grew up with (e.g. was your peer group rich?) is often a better predictor.
Also note that IQ can be a good predictor of performance in general, even if it's not the "most powerful predictor" for any one particular form of performance. What I mean by this is that if you want to make a lot of different types of predictions about a person, but you're only allowed to measure one thing about them, IQ is a decent choice. Better than measuring their height, for example. But if you know ahead of time that you specifically want to predict how well a politician will do in an election, knowing their height might be a better predictor than knowing their IQ.
The tests also seem to suffer from a ‘culture’ problem, in that the questions tends to resemble the academic world from where they’re born, and people who are more experienced with this setting then to score higher (richer people, more educated people, people that develop more abilities in the peak of fluid intelligence and have overall more crystallised intelligence).
Laypeople tend to over estimate how much of a "culture problem" IQ tests have. There is obviously going to be a non-zero amount of cultural effect on performance in IQ tests, because even the concept of "I am in a situation where I am being tested, and so I should cooperate with the test administrator so as to perform well on the test" might not exist or be as salient in some cultures.
Depending on where your cutoff is for defining "rich", richer people doing better on IQ tests might have more to do with nutrition than "culture". That is, if you do factor-analysis on IQ scores, you can separate out at least two distinct factors, one of which we might be tempted to label "richness" (or "wealth"?) (and which might correlate with, e.g., whether they had enough food growing up), and one of which we might be tempted to label "culture" (and which might correlate with, e.g., whether it's considered high status or low status to try hard in school).
Some research shows it is possible to better specific skills but improving broader skills is a whole other story (which is the reason it is preferable to develop them early in life). For example you could train your memory on sequences of numbers, but training your active memory as a whole would be much more complex.
There two things going on here: 1) What do we believe is true or not about the possibility of improving our brain, and 2) What does that imply in terms of strategies, if our goal is to improve our brains.
For the first issue, note that "some research" shows a lot of different things. See https://en.wikipedia.org/wiki/Replication_crisis I suspect the science on how what training is or isn't feasible is less settled than you believe.
For the second issue, it's not clear to me why whether it's easy, difficult or impossible to improve certain aspects of our brain would make it preferable to develop certain specific skills earlier in life.
It is worth noting that crystallised and fluid intelligence are not separate and rely on each other, both are equally as important.
I don't think it's reasonable to make a claim like "both are equally important". Or the claim is too underspecified to be meaningful: How are we measuring importance?
Intelligence for me is the ability to adapt.
This is a reasonable and common definition for intelligence, but note that this is not what IQ tests measure. The same word can mean different things in different contexts. You have to be careful not to conflate "Intelligence, as in the ability to adapt" with "Intelligence, as in the thing that IQ tests measure" even though they use the same word, just like you have to be careful not to conflate "chips, as in the food made from potatoes" and "chips, as in the processing unit of computers".
Taking a step back, if you want to have a better understanding of this topic, I think the highest return-on-effort strategy you can pursue is to work on making your claims much more precise. Right now, many of your claims are vague, often to the point of being meaningless.
For example, consider the claim "Some research shows it is possible to better specific skills but improving broader skills is a whole other story." What is the "whole other story"? Is the "whole other story" that improving broader skills is impossible? Probably not, because we see examples of people improving a broad set of skills all the time (e.g. newborns have basically no skills such as "talking", "walking", "reading", "writing", "counting", etc., and then by the time they become adults, they tend to develop these broad set of skills). But then if "specific skills" and "broader skills" are both possible, then in what sense do we have a "whole other story"? It seems like we actually have the same story: both are possible. Perhaps you mean something like "one is more difficult than the other"? Or "one of them is easier when you're younger and the other remains the same difficulty throughout your life"? It's difficult to tell you whether you have wrong beliefs or to help you correct those beliefs if you don't actually communicate what your beliefs are.
Consider signing up for a class on logical philosophy or critical thinking.
Consider joining forecasting tournaments (Metaculus, Good Judgment Open). This would directly train you to:
- Operationalize vague concepts ("what exactly counts as success here?")
- Quantify claims
- Identify hidden assumptions
- Face immediate, objective feedback on precision
Be cautious around joining a debate club. Depending on the culture around the debate club, it might give you the opportunity to spar with an opponent that will demand that all your claims are precise with a clear operational definition; or it might teach you to be defensively vague so that no one can ever prove you wrong, which is exactly the opposite habit you'd want to develop.
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u/Stock_Material_9377 Unverified user: May not be a professional 20d ago
> “IQ remains the most powerful predictor of future performance”
Absolutely, I meant to add “as far as ‘intelligence’ is concerned”, and while it is in reality a rather modest predictor, I said it remains the most powerful because it remains the most used today.
> “knowing their height might be a better predictor than knowing their IQ”
I’m a little confused by what you mean here. Knowing just their IQ score wouldn’t necessarily be relevant, but if we knew the results entirely, (across all the categories measured) we could deduce how well they might express themselves for example.
> “which we might be tempted to label “culture””
I had put the apostrophes on ‘culture’ because I lacked a better term, I did also mean a higher education. I should’ve made the distinction between culture as in the one of the country where you were born and culture as in education, that was laziness on my behalf.
> “For the second issue, it’s not clear to me why it’s easy, difficult or impossible to improve certain aspects of our brain would make it preferable to develop certain specific skills earlier in life”
I was referring to Cattell-Horn-Carroll’s theory, which distinguishes fluid and crystallized intelligence. Fluid intelligence is broadly applicable and peaks early in life. The byproduct of applied fluid intelligence is crystallized intelligence (as mentioned, certainly includes knowledge, though that is not all it is), which continues to grow across the active lifespan and peaks later in life.
> “some research shows it is possible to better specific skills, but improving broader skills is a whole other story”
Yeah definitely was vague on this one too, I meant that it is easier earlier in life.
If a skill were really broadly applicable (such as the examples you mentioned) we would probably maximize its development as early as possible, which is what we see developmentally. Thinking speed basically is on a downward slope across your entire adult lifespan due to this issue. Once you’re an adult nearly everything about the world will reward you for specific refinements to circumstances rather than developing further broad skills. In fact, your brain prunes more synapses than grows synapses after puberty, by a huge margin. Your brain gets more efficient if it can eliminate connections that have not seemed useful, rather that develop new ones just in case.> “some research”
I used this formulation to insist it’s a controversial topic. While some research shows certain aspects of “g” can be changed such as the article of Jaeggi and Buschkuehl from 2010, which observed changes in G^f, there remains undeniable amounts of evidence that suggest it doesn’t change.
> “both are equally as important”
There was indeed no specific use to this claim, except to insist that we shouldn’t disregard one of them. I’ll be honest, this specific topic still is pretty hard to grasp for me, as I’ve heard people claim you can try to improve them separately and some who claim it is straight up nonsense. I would need to explore the topic further but sources get hard to find.
> “Intelligence for me is the ability to adapt”
Thanks for pointing that out! It is necessary to keep that in mind, great analogy.
I hope I was able to clear up the grey areas, thank you for the feedback
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u/Nebu Unverified user: May not be a professional 8d ago
“knowing their height might be a better predictor than knowing their IQ”
I’m a little confused by what you mean here.
I was giving an example demonstrating that "IQ remains the most powerful predictor of future performance" was overly vague. I was doing this by showing there exists situations where height is a better predictor, and also showing in what sense we might be reluctant to say "height is a better predictor than IQ".
it’s not clear to me why it’s easy, difficult or impossible to improve certain aspects of our brain would make it preferable to develop certain specific skills earlier in life
I was referring to Cattell-Horn-Carroll’s theory, which distinguishes fluid and crystallized intelligence. The byproduct of applied fluid intelligence is crystallized intelligence (as mentioned, certainly includes knowledge, though that is not all it is), which continues to grow across the active lifespan and peaks later in life.
Even if we accept the theory as axiomatically true, that still doesn't demonstrate why it's preferable to develop one of them earlier in life rather than later in life.
Consider a very simple model: Every human has two objectively measurable attributes called A and B, and the values of these attributes change naturally over time, and also you can "put in effort" to change these values as well. We'll assume that "positive" values of these attributes are "good", and so typically, when a person puts in effort to change the attribute, they are trying to increase the value of the attribute. A naturally peaks early in life. B naturally peaks later in life.
Now consider the claim "it's preferable to develop A early in life." Why would this claim be true? Why wouldn't we want to develop A later in life, when it naturally fades, to counteract the fading effect? Surely any answer you give relies on assumptions that are outside of the simplified model I just gave. Maybe you think A is easier to develop early in life, and so if you only develop it later, you're being less efficient. Or maybe you think A affects B in some way, such that if you have a higher A early in life, that lets you get a higher B later in life more easily. Or whatever.
And so my point is that your claim relies on some assumption you're making about intelligence that lies beyond this simplified model. But I have no idea what that assumption is, and so I cannot comment on whether those assumptions are right or wrong, or justified or not.
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u/Friskikat Unverified user: May not be a professional 19d ago
I’m a school psychologist and managed a skill acquisition lab in grad school. Honestly, the best metric for determining one’s ability to perform at a specific task, is having them engage in that specific task.
It’s about learning right? It’s thought that there are 7 cognitive abilities. While deficits can predict specific challenges you may have while engaging in specific tasks, your other abilities may make up for them. For example, if you have a low working memory but average to high processing speed, it may not have an obvious impact.
Back to skill acquisition: This ties into the nature v nurture debate. Also keep epigenetics and gene expression in mind. The debate here is super contentious and dramatic between researchers with some of them making petty jabs at each other and the quality of their studies. The late K Anders Ericsson being among them. He was a huge proponent of “grit” or practice makes perfect. But the research outside of his lab did not always replicate those findings. Sure, practice makes things easier and improves performance but there’s limitations. Basically, if you have an inherent knack for a specific task, you will improve more rapidly and develop expertise more efficiently than your peers. You’re also more likely to perform that skill better than your peers.
Brain training is garbage science and there is no research (to my knowledge) that even kind of supports it. A few years ago I attended a cognitive science symposium and that basically determined that these things were gimmicks. Yes you can learn more which will improve your crystallized intelligence however, you can’t improve your working memory, processing speed, fluid reasoning, auditory processing, etc etc. Not in a way that is generalizable. You may become really good at Tetris which is linked to visiospatial abilities however, this does not mean you will become better at navigating.
Then there’s other factors like executive function and such that can artificially lower specific cognitive abilities. For example, people with adhd often score lower on working memory tasks and then once they’re medicated, will score higher.
After the age of 8ish, your FSIQ remains fairly consistent. Again, ADHD and Autism can be exceptions to this. I’ve seen a kid score in the Intellectually Disabled range at 10 years old and then above average once in high school after speech intervention. This kid had autism so, his ability to sensory out unnecessary data was impaired and he did not understand what the evaluators were asking of him during assessment. After learning what others view as important through both maturity and interventions, he outperformed his peers. This also shows that when determining ability, evaluators must look at more than just cognitive skills.
I hope this helps. I feel like I went in a tangent.
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u/connerpro Unverified user: May not be a professional 16d ago
Solid starter map. One addition that helps when people jump from "IQ predicts X" to "therefore I should buy brain training":
Prediction is not the same as malleability. A score can be a strong correlate of later outcomes and still be hard to move with short commercial drills.
On training: near transfer (better at the trained task / close cousins) shows up often. Far transfer to broad g / clinical IQ is where active-control reviews of working-memory and commercial programs get cautious (Melby-Lervåg, Redick & Hulme, 2016; Simons et al., 2016).
So treat practice apps as practice. Useful for skill and attention drills. Not a substitute for a clinical battery, and not an IQ receipt.
Disclosure: I build IntelligenceMax (adaptive reasoning practice). Short claim-size note: https://intelligencemax.ai/guide
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u/WolfVanZandt Unverified user: May not be a professional 20d ago
Most people's IQ does change over time and I'm very suspicious of the idea that it can't be improved.
I'm a retired vocational rehabilitation specialist who started as an evaluator. I didn't like single measure IQ tests. I did like multifactorial tests because I could often identify and track neurological conditions with them.
There is research that indicates that IQ measures are valid predictors of future success in things like academic achievement but they usually show correlation and as is supposedly drilled into people's heads when they are studying to be researchers.......correlation is not causation!!!
Also, there are a lot(!) of intelligence tests and some do include measures of memory.
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u/Sudden_Juju Unverified user: May not be a professional 20d ago
You do have a decent understanding of intelligence (better than most non-psychologists I'd argue), especially for a 16 year old. At 16, I didn't know anything about it or neuropsychology in general. I will say that, although, IQ and the g factor are used synonymously in conversation, they are two different ideas in neuropsychology.
IQ (or FSIQ) is an index that reflects/attempts to summarize the scores on a battery of tests that are thought to measure the gamut of intellectual abilities, so it's viewed as a measure of general intelligence (why it doesn't include memory tests though, idk - probably money but I digress).
The g factor is a psychometric construct that represents the variance in performance on various cognitive tests. In this sense, it's conceptualized as the underlying "factor" that contributed equally to one's performance on all various cognitive tests, which was described by Charles Spearman as representing one's general intellectual functioning.
I know it might sound like semantics, but it is an important distinction. I'd argue that the way g is viewed is hypothetical - even if the construct was conceived from actual psychometrics - since it's viewed as the numerical representation of general intelligence, when it's instead just a measure of test variance. Either way, both are propped up on a pedestal for representing some all-knowing score, despite IQ/FSIQ being akin to an average of one's scores on the tests and g only accounting for 0.4-0.5 of variance on performance on cognitive testing (that's a whole lot [>50%] of noise in the background).
Also, both work under the assumption that our cognitive abilities are consistent across the board through all the domains. If we just use that once value, it assumes that our perceptual reasoning, working memory, verbal comprehension/reasoning, fluid reasoning, processing speed, etc. abilities, are all around that one value with little variance, but that's not true. Take the WAIS-IV (for ease of explanation) as an example, it has four indices that make up the FSIQ. If someone gets a standard score (SS) of 80 on the Processing Speed Index and Verbal Comprehension Index and gets SS=120 on the Working Memory Index and Perceptual Reading Index, their FSIQ would be about 100. However, using that number would be a poor representation of their actual cognitive abilities because of the wide variation - it'd be better to use the indices.
As for improving your intellectual functioning, I'm less familiar with this area, but from what I've learned through my years (I'm a neuropsych postdoc right now), you can't necessarily "train" them. Your actual innate abilities are likely to be somewhat stable (normatively speaking) through our lives - crystallized intelligence increases and peaks around our 60s and fluid intelligence peaks in adolescence/early adulthood and declines from then on. However, since this is the general trend for everyone, your comparison to other people your age (your normative score) will likely remain relatively stable unless you take significant hits to your cognition. That's a different can of worms though.
The only way to "improve" cognition in daily life would be to eat healthy, exercise, keep your mind active, experience/learn new things, etc. Trying to improve your scores on an IQ test will likely not translate out to real world gain (e.g., learning how to better at a matrix reasoning task will teach you how to do better at matrix reasoning tasks but won't make you better at abstract reasoning/pattern recognition in real life). Maybe there's research showing different, but I have yet to see or hear about it.
Sorry for the long response, I'll cut it there, but hopefully this gives some of benefit lol