Is there scientific evidence that IQ tests measure intelligence? [duplicate]

IQ tests are quite popular, but they seem to be lacking a scientific proof confirming their accuracy of measuring ones intelligence.

No matter how hard I've searched I haven't been able to find a scientific paper proving the result, all I could find was some questionable statistical studies but I am not interested in such, I am looking for a more fundamental proof, one that shows the relation of this test with the actual biological processes in the brain.

My guess would be that the only thing IQ tests measure is how good someone is at IQ tests, since one can actually get a good score due to training.

Another thing to keep in mind is that, people working in mathematics, physics and related sciences tend to get better scores and this can be explained by the fact that this is what they do, this is their job and they have spent a large amount of time studying patterns, but this however does not mean that they are necessarily smarter that others they are just trained at this.

A mathematician for example, given a sequence 2,3,5,7,... can see that the next term is 11 since this is a familiar sequence to him, but to an artist it may not be familiar at all.

Having said that, do IQ tests actually measure human intelligence? Is there a strict proof that confirms this?

• If you want to test whether IQ measures intelligence, you have to measure intelligence. How do you propose to do so? Commented May 17, 2021 at 17:13
• I am not an expert so I can't propose anything, this is just a question, in fact I work at something completely different, but given that we don't know how to measure intelligence then claiming that IQ tests do is absurd.
– user28534
Commented May 17, 2021 at 17:18
• I'd suggest reading the Wikipedia page on IQ: en.wikipedia.org/wiki/Intelligence_quotient I think it will show you that you're not alone in your concerns, but also explain what IQ really is. en.wikipedia.org/wiki/All_models_are_wrong may be worth a read as well. Commented May 17, 2021 at 18:09
• I agree with @BryanKrause that this question is not well defined - ie, what proof is there that any test measures what it purports to measure? In any case, I think this question is a duplicate of: What is the relation between measures, constructs and concepts? Commented Jun 20, 2021 at 7:25
• @Kthamil You're suggesting a mathematician would ace an IQ test by virtue of being a mathematician. You're looking at it the wrong way, he is a mathematician because he is intelligent. So, in your example, he would be acing the IQ test due to his intelligence, not his occupation. Commented Jun 21, 2021 at 4:54

It depends on the way intelligence is defined (which can be discipline-specific). For example, in the field of clinical psychology, intelligence is defined as a statistical correlation between different tasks that require intellectual (again, as agreed upon) effort.

If you define intelligence as correlations between different tasks that require "intellectual effort", then yes, but why would someone choose to do stuff like this for their job in the first place? Clinical psychologists/geneticists proposed (as you implied/hinted at in your post) that since the heritability of IQ increases with age, that it's as a sort-of feedback loop where people with a rough "heritable" edge seek more and more environments that reinforce those skills (Robert Plomin did work on this I believe).

For a fundemental take I would try and look up The Neuroscience of Intelligence by Richard J. Haier, one of the more "fundemental" results he found is that the people who scored better on certain IQ tests had more calory efficient brains, the heat of the brains correlated negatively with the test scores. But again, maybe that is still a post-hoc thing.

• Haier also describes the abstract nature of "intelligence", of which the definition is a fundamental issue in discussions of measurement
– pep
Commented Jun 25, 2021 at 14:13

There is no universally accepted definition of "intelligence", so there is no universally accepted measure of it. An IQ test can be argued to measure specific types of intelligence like pattern recognition, but may completely ignore other types of intelligence like creativity and social intelligence. IQ has been shown to be associated with many factors like income, educational attainment, job performance and incarceration rates, so IQ tests clearly measures something meaningful and associated with many aspects of one's life, but whether you call that "intelligence" is open to debate. It's reasonably well accepted that an IQ test can measure specific kinds of intelligence, but there is no way to even define, much less quantify, intelligence in a general sense.

• What are the research papers that IQ tests clearly measure something meaningful? Can you provide some studies? My question was to provide literature.
– user28534
Commented May 17, 2021 at 17:28