[antmldr]

Having been on the receiving end of this as a candidate (not at IBM), everyone was in on the test in the first 15 seconds, and it changed people's behavior instantly.

It's fairly obvious if you're on the receiving end what the purpose of the test is when you're being observed (as with most interview questions, it helps to ask yourself why the interviewer asking me / having me do this?)

[brimble]

Like with those "personality tests" where anyone with decent perception and reading comprehension can easily tell which outcomes each answer's going to push them toward, and so obtain any result they like.