No answer! Well. Replace the tests with some respectable source of information, and think again.
Imagine you realize your confidence being lower than the situation would warrant. You immediately adjust your confidence up a notch and start living bravely and proudly, being successful in many new tasks. If confidence is just information based self-evaluation, becoming aware of it would facilitate immediate correction.
Then there's the camp that promotes high confidence as just something required, never mind if you've got nothing to be confident about. High confidence is seen as a tool that enables a person to start difficult tasks and persist, while enjoying their time doing them.
No wonder it's recommended for all. Never mind that unreasonably confident, mentally blind individuals can be a major pain in the butt. It's others that suffer, the one with high confidence will happily disregard evidence pointing to their failure.
I got sidetracked. I wasn't looking for self-help, but Edahn seems to have a clue. Low confidence might really be a belief of failure, blessing the person's habits of non-action and giving them comfort in not trying.