I heard a piece on NPR that covered this. The full transcript is here; the relevant quotation that stuck in my mind was:
An interesting example of that is the U.S. military uses a test called the ASVAB to screen young recruits when they're just coming out of high school and they don't know much about them. And historically, at times when the Army has let people in who've scored the equivalent of below an 80 on an IQ test, the Army has been rendered less efficient, so the troops don't follow orders as well, they can't figure out complex machinery like tanks or read maps.
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u/Dr3adpirate Dec 18 '19
Source?