I don’t know about Norway, but here in Spain the % of people who sign up to the military who are immigrants has been steadily increasing these decades, so a drop in IQ does not surprise me at all.
"Why would immigrants have a lower IQ than native spaniards?"
The commenter should not be down voted.
Different ethnic groups have measurably different IQ's.
Ethnicity represents genes, but also a myriad of other behaviours, attitudes, perspectives: all of the 'possible differentiators' mentioned in the article could easily be accounted for simply by ethnicity. Westerners more likely to play video games, some other group more or less likely to sleep, yet another group may or not value reading or eduction. In some groups women don't play any sports, maybe the lack of activity causes differences.
Most immigrants to Spain come from poor countries with low levels of education and generally lower IQs.
Though it's a really uncomfortable bit of reality, and we don't want to provide cover for bold racism - the position that 'immigrants might be lowering (or improving, even) the IQ results' is a reasonable hypothesis on the face of it.
In TFA it says this drop in IQ was detected because of tests done to people who sign up to the military. I’m talking about how there are more and more immigrants joining the military here as years pass and that if in Norway the same is happening it’s normal that IQ is dropping as I expect immigrants to have a lower IQ than natives.
This language barrier is partially what motivated the development of the Raven progressive matrices test. The test was used by the UK military to judge recruits without creating a bias based off of the recruits language.
If the controversial citations in the article you cited are true (which I haven't read in detail, but seem questionable at a glance.) - unless the predominant amount of individuals immigrating into Spain/Norway are coming from countries with lower average IQs I would not expect it to have an effect on the average IQ of Spain/Norway.
It also stands to reason that there is no reason to assume Spain is at the top of the chart when it comes to national average - so they are most likely also having immigration from countries with a higher average. This would mitigate the effect of countries with a lower average, would it not?
Returning to the original point:
Because immigration usually entails an amount of merit and ability - the successful immigrants are usually at the higher end of the capability spectrum of the originating countries population.
Doesn't it stand to reason immigration would have either a minuscule or positive effect on national average IQ?
Maybe pre-2015, but since the European Migrant Crisis, there has been a disproportionate amount of migration from sub-Saharan Africa, which is the region that scores lowest in those surveys.
Also, does Spain only administer IQ tests to members of the military?
Or are you saying that members of the military have a lower IQ than the rest of the population?