When researching my 2004 article on John F. Kerry's and George W. Bush's IQ scores judging from their performance on the Officer's Qualification Tests they took in the later 1960s (Bush 120-125, Kerry 115-120, which turned out to fit with their GPAs at Yale), I read a lot of studies from the 1960s by the military's psychometricians documenting the predictive validity of these exams. I then tried to track down the authors to help me understand Kerry's and Bush's scores.
I spent two hours on the phone with a very helpful gentleman, now a college professor of statistics, who had retired after many years as the head psychometrician for one of the major branches of the Armed Services.
Among much else that was interesting, he mentioned that in 1990 he had provided to Charles Murray the U.S. military's scores from the renorming of its AFQT enlistment test. In 1980, the Pentagon had paid the Department of Labor to give the AFQT to all 12,000+ young people in its National Longitudinal Study of Youth database. The middle section of The Bell Curve is devoted to tracking how these ex-youths, now 25 to 33 in 1990, were doing in life in relation to their IQ scores a decade before.
My source had nothing but praise for The Bell Curve.
The psychometric expert said something that seemed puzzling to me. He said that the General Factor of intelligence completely dominated job performance as a pilot to such an extent that it really wasn't worthwhile to give multiple intelligences tests of specific piloting skills, such as the one George W. Bush took in 1968 to measure his 3-d visualization skills.
For example, a question might ask:
Which picture represents how the horizon would look straight-ahead out the cockpit window when you are in the midst of turning from flying north to flying east while banking 60 degrees?
Bush only scored, I believe, at the 25th percentile on this test, but I don't think this kind of thing came up much in the Oval Office.
My source said that he recommended getting rid of flying-specific tests for admission to pilot-training, but the brass wouldn't go along with it because they insisted their had to be pilot-specific skills separate from the g Factor.
Listening to him, I certainly agreed with the brass. After all, I have a decent IQ, but I'd make a terrible pilot during the brief interval before I became a smoking crater due to making some stupid mistake.
And, this is not something I only recently realized. I can vaguely recall being 16 and looking at the catalog from the Air Force Academy and deciding that, based on my experience driving a car, riding a bike, playing sports, and generally bumbling about in the physical world, that I wasn't cut out to pilot Air Force jets.
I've wondered about this expert's finding over the years, and I think I've finally started to figure it out: People with high IQs who would be bad pilots generally figure out for themselves that they would be bad pilots; so, they never take the tests to be pilots. Thus, the high correlation between the g Factor and pilot performance: high IQ individuals are already selected for having pilot-specific skills.
Similarly, high IQ guys who would make lousy firemen already know it, so they don't take the firemen's test much.
Thus, a hiring test like the New York ones ruled too discriminating by Judge Garaufis tend to work well. They are combination aptitude and achievement tests with all the questions solely about firefighting, but all the information needed to answer the questions given on the test. Still, under pressure, it's not too easy to decipher passages about technical details of chainsaw maintenance.
Thus, to score perfectly on these kind of tests, it's helpful to be both reasonably bright and to have studied firefighting guidebooks. High IQ guys who wouldn't make good firemen tend to figure out while they're studying that this isn't the career for them and thus don't take the tests. So, these kind of aptitude/achievement tests work quite well.