Some of the difference in scores will be driven by differences in g, some by differences in motivation, some by education, etc. There are tests that, controllin

Some of the difference in scores will be driven by differences in g, some by differences in motivation, some by education, etc. There are tests that, controlling for motivation, do a pretty good job of getting around this (like Raven's progressive matrices, etc.) They don't even require language. I think you're on the right track, though. But the key sticking point is this: many people are very uncomfortable with the idea that there are differences in intelligence among people, both within and between populations. Unfortunately, that is undeniably true. And so we get this ridiculous, unproductive dance. Also, just as an aside, the latest evidence around the "poverty actually makes you literally stupider" claim is that it's not supported--studies aren't replicating. Which makes sense because the claim is prima facie crazy, but I digress...