As an European, I did never have any IQ test, nor I know anybody who (to my knowledge) was ever administered an IQ test. I looked at some fac-simile IQ tests on the internet, expecially Raven's matrices.
When I began to read online blogs from the United States, I started to see references to the concept of IQ. I am very confused by the fact that the IQ score seems to be treated as a stable, intrinsic charachteristic of an individual (like the height or the visual acuity).
When you costantly practice some task, you usually become better at that task. I imagine that there exists a finite number of ideas required to solve Raven matrices: even when someone invents new Raven matrices for making new IQ tests, he will do so by remixing the ideas used for previous Raven matrices, because -as Cardano said- "there is practically no new idea which one may bring forward".
The IQ score is the result of an exam, much like school grades. But it is generally understood that school grades are influenced by how much effort you put in the preparation for the exam, by how much your family cares for your grades, and so on. I expect school grades to be fairly correlated to income, or to other mesures of "success".
In a hypothetical society in which all children had to learn chess, and being bad at chess was regarded as a shame, I guess that the ELO chess ratings of 17 year olds would be highly correlated with later achievements. Are IQ tests the only exception to the rule that your grade in an exam is influenced by how much you prepare for that exam? Is there a sense in which IQ is a more "intrinsic" quantity than, for example, the AP exam score, or the ELO chess rating?
I heard at local Mensa that there is a guy who keeps coming to take the IQ test every year, and every year he fails to pass the Mensa limit. And he's been doing this at least for a decade.
For me, it is difficult to imagine, because Raven's matrices (the IQ test my local Mensa usually uses) is like the same two or three patterns over and over again. How could anyone take the test twice without noticing this? And if you notice the pattern, then you should get at least 80% of questions right very easily, which probably should be enough to pass the Mensa limit...
...but then, from my perspective, it doesn't make sense how anyone could get a result other than "random answers" and "almost everything correct", and yet apparently most people end up somewhere in between, which means that I am confused about something.
Maybe noticing that "it's the same two or three patterns over and over again" is how high IQ feels from inside; and if you have average IQ, it just seems like a sequence of independent puzzles with increasing difficulty, dunno. Or maybe most people only take the test once, and essentially run out of time before they recognize the repetitive pattern, and don't take the second try where they could score higher by applying the knowledge of (the existence of) the pattern from the very beginning. Or a bit of both.
By the way, after you do the test, you are told the IQ and maybe the number of questions you answered correctly, but you are not told which ones you answered wrong and what was the correct answer. So if your problem was lack of time, then repetition can help... but if your problem was being unable to tell the difference between the right and wrong answer, then repetition does not help. (Other than introducing some random noise, so if your real IQ is e.g. 120, if you roll the dice often, once you get lucky on the questions you answered randomly, and pass the 130 limit -- but that's not "getting better" in the strict sense.)