Not pilot aptitude testing, but ATCO aptitude testing... but I hope you find something useful in amongst all this lot.
Background: Eurocontrol's aptitude tests give you a points score from 0 to ????. The pass mark is 587, but nobody has ever been invited back to further selection with a score of less than 610.
There are 5 people in this narrative, with scores 920, 830, 784, 785, and 650(ish).
920 has been doing consistently well throughout the training. 830 is really flagging. 785 is doing very well indeed after a slow start. 784 started slow, carried on slow, slowed down and nearly got kicked off the course. However 784 has recently picked it up. 650(ish) is, by all accounts, doing rather well (and in the previous assessment was doing better than an 880(ish) person).
... make your own conclusions there. I have heard of validated controllers in Maastricht who failed NATS aptitude tests and vice versa.
I have repeatedly failed Cabair selection tests, but passed Oxford (BM) selection tests. On all check flights/ flight tests that I've taken I have never failed (although come close to it once, but the reason I didn't was because I kept a good attitude and didn't lose it like other 30-something hr PPL students might do, according to the examiner).
I personally believe that aptitude tests can give you an indication of how well someone will do in the training, and whether there is anything there to build on. A good instructor will inspire confidence in the trainee / student, which is very, very, very important.