They're normalized on average IQ for the populations in which they were originally designed. That is, mainly, British and American schoolchildren and (later) adults.To perpetuate the tangent, I was under the impression that IQ tests were normalized so the average IQ is, by definition, 100 (for the group they're normalized on). If that isn't the case even in the US, do you know what population the tests are normalized on?
But average IQ is not the same in all populations. If the tests had originally been normed for Ashkenazic Jews, 100 would correspond to about 117 on the now-established scale. Or for Northeast Asians (Chinese/Japanese/Koreans), about 110. Though interpreting that number is trickier than it looks because Northeast Asians skew higher on visual intelligence while having a very similar distribution of verbal intelligence to non-Ashkenazic Brits and Americans.
I won't list any of the populations that have lower average IQs than the baseline 100, because people who can't handle facts very well tend to start screaming "racist" when you do that. Besides, that isn't necessary to explain my previous remarks. I'll just note that the world median is significantly below 100 and leave it at that - you can easily dig up the figure for yourself, but prepare to be shocked if you do. There are a few places (blessedly few) where average IQ is down in the 50s and 60s. They are, not by coincidence, hellholes.
They're hellholes for the same reason the average IQ of an occupying force matters. A trait very strongly tied to higher IQ is lower time preference - that is, the ability to defer or entirely forgo immediate gratification for a larger future reward. If your troops have high time preference, they will tend to loot, burn and rape for immediate gratification because they weight the immediate reward against the future risks differently than a person with low time preference would. That's assuming you enforce consequences for bad behavior in your troops; if you're (say) Japanese of this time period, maybe you don't.
So: an occupying force of Ashkenazic Jews would have been slightly better behaved than the Brits, Americans, and Canadians were, because higher average IQ and lower time preference. Conversely, if you drew your occupying troops from any of the populations with lower average IQ that I'm carefully not going to go anywhere near identifying, they would have had higher time preference and relations with the locals would probably have gone a great deal worse. If I wanted to start a shitstorm, I could name examples from WWII.
(And just to head off another possible source of screaming, none of these predictions depend on why populations have the average IQs that they do. You can assume culture or genetics or childhood nutrition or even a dastardly plot by colonialist exploiters, and it doesn't matter; the predictable consequences of differences in time preference in terms of bad behavior by your troops will not change.)