I wonder if the act of answering the question actually causes the decision to firm up. Kind of the OvercomingBias Uncertainty Principle.
Sounds like good old cognitive dissonance. Your mental model was not matching the information being presented.
That feeling of cognitive dissonance is a piece of information to be considered in arriving at your decision. If something doesn't feel right, usually either te model or the facts are wrong or incomplete.
The depressed are less biased in their self-assessments than the population as a whole.
Can that be true? What about their assessments of the rest of the world outside themselves? My experience with depressed people runs very counter to that. Do you have any references to that?
M. Scott Peck in the Road Less Traveled says something like, "Mental health is a commitment to reality at any cost."
Gendlin's take on it is spot on too.
I have an article that I'm writing on that in my emotionsforengineers blogspot.
I will definitely link to this site as well.