What do IQ tests determine?

What are the limitations of IQ tests/testing? What external (and other) factors affect your IQ score and how do you negate their effect? How does mental state/health/illness affect your IQ score?

• I'm a layperson and I'm only asking this out of curiosity. If there are flaws in my arguments/statements, please correct them as I would like to learn more. If you think the title should be edited, please do so. Coming to the point, a person whose innate intelligence (again this depends on what you mean by intelligence) is high might score rather low if he's in depression or if he experienced emotional trauma in his life as a result of which his mind is full of intrusive thoughts. A mentally ill person (say a schizophrenic or someone with OCD) might score rather low or high based on his/her mental state during evaluation. Someone with bipolar disorder might have a mind that functions slowly when in depression but pretty quickly when in a state of hypomania/mania. Someone with performance anxiety might not score well either. Besides that, even "normal" people might have different levels of functionality during different times. For example, when doing pattern recognition questions they might be able to spot patterns quickly sometimes while not so quickly at other times. Same goes with memory recall. All this might be true even if you take precautions to avoid these pitfalls (although precautions may improve the accuracy of IQ measurement). So how exactly do you take these factors into account while measuring IQ? What precautions do you take? Do you take multiple IQ tests at different times to come up with a clearer picture? Other than what I mentioned, what are some other limitations of IQ tests? Richard Feynman and James Watson scored something like 125 and 120 respectively if I remember correctly but they were/are esteemed scientists. These aren't great scores at all. I'm pretty sure their pattern recognition skills etc. were/are pretty good. Although, maybe the tests they took could've been pretty outdated or there were other factors at play or maybe there's something I'm not thinking about altogether.

• Answer:

  IQ tests are notorious for being culturally biased. The values of one culture don't necessarily equate with the values of another. In a poor village an intelligent man may be viewed as one who can build a house with the few available resources while in the same village a man who is a mathematical prodigy may be viewed at best as a useless idiot. Pracrical intelligence is just something that isn't capable of being taken into account in the standard academic test format of the West. Creativity is also a highly valued trait across the world which is almost completely disregarded by IQ tests. Doing well on one may only really say that you had a clear mind that day, that you are excellent at taking timed tests and that you have rigorously studied the standard curriculum of most Western schools. IQ tests aren't complete rubbish, they can help people pinpoint certain intellectual faults in terms of mathematics, etc. but like all other social measurements it is not the be-all, end-all that some of us would like it to be in regards to intelligence.