How does IQ test actually work?
In: Biology
Alot of good answers here, but I think the key to keep in mind is to ask the question, “What is intelligence?” If intelligence is how well or how efficiently you can solve certain puzzles or problems then our current method for testing and measurement makes sense. But in reality, intelligence is far more complex than that, and thus our manner of measurement is not all that accurate. There’s still debate as to how we define intelligence and how we therefore measure it. At the end of the day, we don’t have a better solution to this problem so our current IQ testing is the best we have, but there are some interesting arguments being made for new ways of defining and measuring IQ.
I’m a preschool level school psychologist. I regularly give IQ tests to five year olds.
In case anyone is curious, here is how I actually explain IQ tests to five year olds…
We’re gonna play some games that will tell me how your brain works. Some people’s brains think best with pictures, some with words, some with sounds. Everyone’s brain is different and that is what makes us special. We are going to see how your brain works best so we can make it easier for you to learn at school. All you need to do is just try your best. Do you have any questions?
Source: I’ve actually taken an IQ test.
Functionally, you’re asked to perform a variety of tasks that test various abilities: general knowledge (through questions), hand-to-eye coordination, short and long-term memory, language…among other things. There were generally two tests per area..
One test I remember involved the examiner giving you two words,at which point you were asked to point out the commonalities between both of them (eg ‘blue’ and ‘red’ are both colors).
An IQ test takes about 1-2 hours to complete; AFAIK your results are used to compute a score for each tested ability, which are then used to find an overall IQ score.
One thing I will point out: as a society we’ve grown to see IQ tests as not much more than a tool used for gloating, as a way to measure intelligence in some for or another. The reality is that IQ tests are important medical tools which can be used to find out and quantify developmental issues in people: “intelligence” may be a debatable concept, short term memory is not.
Alright, a lot of good explanations, but not a lot of “explaining like I’m 5”. The most popular IQ test is the WISC V. Usually, these tests are conducted in a 1 on 1 setting over the course of about 1-2 hours. There are multiple subtests which measure “intelligence” in 5 different ways. Visual Spatial (Ex. manipulating blocks to match a pattern), Processing Speed (Ex. Figure out a code with a symbol key), Verbal Comprehension (Ex. Vocab knowledge) Fluid Reasoning (Deductive reasoning skills), and Working Memory (Remembering numbers). Based on your score from all the subtests, you “add” them all up to make a Full Scale IQ. Full Scales IQ’s have an average of 100 and a standard deviation of 15. Meaning that most of the population lies between a score of 85 and 115. Like many people have said, an IQ test is not a representation of someones complete intelligence. For instance, someone could be a complete genius in painting or music, and the IQ test would never pick that up. However, the IQ test does measure abilities that are correlated with being able to navigate the modern world with success.
Source: Am a School Psychologist and give IQ tests for a living.
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does the test measure anything aside from how good you are at the test itself? i mean, is there any scientific basis that these puzzles are decent proxies for other aspects of cognition?
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I’m going try a real “explain like I’m 5” answer. A more adult-level (and accurate) response is given by /u/pgok15 below. I’m also a PhD researcher in educational measurement.
How does an IQ test actually work?
There’s a lot to think about with that simple question! I’m going to start with something more familiar, and that’s a scale for measuring weight. Imagine you’re way back in the past and you have to invent a scale from scratch. You want to know, for example, how much a sack of potatoes weighs at the market so that you know how much to pay a farmer. You can tell just by lifting that one sack is heavier than another sack, but that’s about it. So at some point people figured out a balance scale – like a seesaw that you can put things on either end of. If both ends weight the same, the scale is balanced. If one side is heavier, it tips toward that side.
This is great, because now we can compare our sack of potatoes to a “standard” measure. We can, for example, keep weighing a bunch of stones against one another, chipping a little here and there, until we get a whole bunch of stones that all weigh the same as one another (our balance scale is really good at telling us when things are of equal weight). Now we can say this sack of potatoes weighs as much as 4 stones, and that sack of potatoes weighs the same as 6 stones. Progress!
So now we have a “test” that can tell us how much something weighs, by comparing it to other things that we already know the weight of.
I’ll point out here that we don’t have to have a deep scientific knowledge of what weight actually means. In fact, our ideas about why things have weight at all has changed a lot over the centuries. But all during that time, famers still managed to use scales to figure out weight without knowing exactly what weight mean. All they cared about was how to use weight to get some business done.
Now we’ve got a similar problem trying to figure out “intelligence”, except intelligence is a little more complicated than “weight.” It’s a little like talking about the “yumminess” of a meal – ice cream can be yummy, but so can pancakes, and so can a hot dog. They all taste different, and you probably don’t want hot dogs for dessert and ice cream for breakfast (maybe you do?), but you can definitely tell “yummy” food from “yucky” food. Overall, when you ask for food, you want yummy food, not yucky food, and it would be great if the person making your meal understood the difference.
Wiith intelligence, we can see with our own eyes that some people are more clever than others at certain things. One person might be awesome at setting snares to catch rabbits, another person is really great at composing songs, while someone else can figure how how many potatoes we need to plant for the winter without wasting any. Each of these demonstrate some sort of intelligence. They may look like very different jobs, but underneath we can tell when something is “intelligently” or “stupidly” done. And in general, when we ask someone to do something for us, we want them to do it intelligently, not stupidly.
So how do we measure intelligence? It’s like the problem of weighing potatoes – we need a standard. So we come up with a standard set of tasks for someone to do – solve mazes, talk about patterns in a picture, copy complicated shapes with tiles, or explain some complicated text. What we then notice is that people who are good at, say, copying a complicated shape with tiles – these people also tend to be really good at figuring out how to plan a harvest or design a building. The people who can read and explain complicated text also tend to be good at composing songs or understanding how other people feel. When we find tasks that tend to go along with other skills that we care about we treat those tasks like the stones we use to weigh potatoes. After all, we don’t really care how well someone can solve a maze puzzle – what we care about is what being good at solving maze puzzles predicts about other performance.
Like the potato example, we can be a little fuzzy on the concept of what intelligence actually *is*. That is, I don’t know what weight *is* the same way a physicist does, but I know how to *use* weight in my day-to-day life, and I care a lot about getting an accurate number on my scale. I don’t know what intelligence *is* deep down, but I do care that when I ask someone to figure out where to build a hospital, or how much to plant for the next season, or to help negotiate a treaty with the next tribe, that I want someone who is skillful at these tasks.
That’s the key concept here – we’ve come up with this sort of shortcut concept called “intelligence” to stand in for skillfulness on a variety or tasks, just like we haver “yumminess” as a rough measure of the quality of food, whether it’s ice cream or a hot dog. IQ tests have their origins in trying to figure out who will be good at doing what sorts of tasks, without taking months or years to actually watch them try out all these tasks. Instead, we found a bunch of short puzzles that tend to predict how well people do things we actually care about.
So here’s your answer: once we agree on what we mean by “intelligence” (and different groups of people may have slightly different definitions), and how we can describe “intelligent” vs “stupid” ways of doing things, we look for shortcuts that give us a rough idea how well a person might do on future tasks. Because over time these shortcut puzzles have worked well for predicting real-world performance, we’ve come to believe they describe some hidden quality of a person called “intelligence”.
Again, I don’t know what weight is deep down inside, I just know how it matters in the world. Same with intelligence – I don’t know what it really *is* at a fundamental level, but usually we can agree on when we see it or now.
(I’ve got to run and cut this short – I may come back to edit).
I think other people have explained it deeper than me, but I’ll give it a shot anyways.
We *assume* recognizing patterns means that you are smart. We then create a series of patterns with 1 picture missing and ask you to fill it in. If you can recognize the pattern, you are smart. If you cannot recognize the pattern, you are not smart.
Keep in mind, as everyone will tell you, IQ doesn’t necessarily mean smart, and **certainly** doesn’t mean smart in every sense of the word.
Brief background, I am a PhD researcher in psychology and I have published papers on intelligence, and particularly the Flynn effect which is the increase in measured intelligence found in most countries.
This is long so I’m putting the most important thing first: your IQ is not your worth. People have an inherent dignity that is equal and inviolable regardless of how smart you are. Albert Einstein does not have more value as a person than someone who is incapable of tying their own shoelaces. I think people get really defensive about IQ and intelligence because our society values intelligence to an extraordinary degree. If IQ tests do what they purport then (1) people are not equal on this valuable trait and (2) we can objectively determine who does and does not have more or less of this valuable trait. People then start to think that we have a test that we might try using to determine someone’s worth, but your IQ *does not determine your worth.* Your IQ determines your value as a person as much as your height does, which is not at all.
IQ tests today are typically either something like Ravens progressive matrices, which are a series of pictorial puzzles of increasing difficulty, or they are somewhat more traditional tests that include a variety of problems centered broadly around “reasoning”. Modern tests are highly sophisticated instruments subjected to very rigorous statistical methods to ensure a few things (1) that the measure what they say they measure (2) that they do so in an unbiased way and (3) that they do so accurately. “How do IQ tests actually work?” Well, after the test is developed you take the test, the test is scored (this can be either a simple summary, or for more sophisticated tests, a score that takes into account the difficulty of the specific questions you answered correctly, how well they tend to distinguish high from low IQ individuals, how well they measure IQ etc.). This score is then compared to some “norm”. A norm is simply the distribution of scores for some group of people (say 20-30 year olds, measured in 2020). Your score lies somewhere in that distribution and we tell you where you stand compared to everyone else. Usually this score is adjusted so that the average person has a score of 100 and the standard deviation (kind of like the average difference from the average) is usually either 15 or 16 points.
How do we decide that the tests measure intelligence? Well, do they predict outcomes that we would expect to occur based on differences in intelligence? For example, if you have a job that requires a “smart person” do people who have high IQ’s tend to do better in that job? (The answer is yes.) IQ tests are predictive of a number of things that we tend to associate with “intelligence” as a concept. Higher IQ is generally predictive of higher levels of education (i.e., *before you get the education you have a higher IQ*). Higher IQ is generally predictive of better job performance in jobs that require critical thinking and an ability to solve complex problems. It is predictive of maintaining your health better, etc. *This is not to say that IQ is the only predictor of these things*. However, IQ is one of the best psychological predictors of these things, generally speaking the only other psychological construct that comes close to having the same kind of predictive ability is Conscientiousness (which is, roughly, your ability to act in a way that is considerate of others). IQ is also predictive *above and beyond* things that people commonly raise as being what IQ really measures (particularly socieoconomic status).
You’re going to get a lot of comments to the effect of “we don’t really know what IQ tests measure” or “IQ tests don’t really predict anything.” That’s pretty much categorically false, and not a position held by the vast majority of intelligence researchers. It’s a fairly anti-science position, bluntly. Most of it appears to come from Stephen Gould’s “The mismeasure of man.” That book was pretty widely criticized by pretty much the entire community of intelligence researchers. The issues he raised were either (1) his own misunderstandings of the science, (2) out of date, or (3) flatly wrong. You will see a lot of people say “well you take a standardized test with multiple choice answers, but life doesn’t have multiple choice answers, so really that’s meaningless.” No, it’s not. The tests are designed to test your ability to use information and solve problems, that you can choose from a variety of answers doesn’t change that you’re solving the problem, it’s just far more convenient from a test creation perspective.
Again though, because I can’t say it enough, these tests do not, will not, and cannot, determine your worth as a person. A smart person can be a monster, and a dumb person can be a saint, which one you are really doesn’t depend on how smart you are.
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