Tendency wouldn't mean absolute causality. Not true in one anecdotal case is different than something being wrong. I think you can find most of Frank22's points fairly well layed out in the book: Essentials of WISC-IV Assessment.

per KADMom's question:
"So did I misunderstand your original assertion that a person's personality trait of meticulousness lowers their PSI and inflates the other three indices?"

I think that is the inverse of what he originally was saying, which was that if the other three indexes are high and PSI is low, FSIQ is still a reliable measure. I think the statistics say that, and the presented supporting theory behind the statistics is that perfectionism can yield that pattern. I think block design can be a bit of a wash because it is timed, but it also favors a more complex carefulness to prevent accidental mistakes.

Of course it has been over twenty years since I took psychological testing, test design, and various statistics classes; techniques and theories (and my memory) may have changed radically since then.

And above all, most of us here are here because our kids are the exceptions that statistics do not account for. 1 in 10,000 isn't even noise in most of these test norms.

Welcome to the boards, Frank22.