How does IQ test actually work?
In: Biology
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).
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