And then you go to update, you compute the desired behavior to maximize utility... and some cognitive module buried in your brain says "no".
I realize I need a physical examination. I have no rational reason to fear going to the doctor. I am, in fact, acutely aware that my fear of going to the doctor is based on a fear that they will find something wrong that I can't afford to fix, but the truth is already so. So I bite the bullet, make an appointment, and then at the scheduled time I get in the car and drive to the doctor's office.
And then I just keep driving past the doctor's office, turn around and go home.
I tell myself that if I'm not going, I should call the doctor to avoid a $100 no-show fee, but I don't.
And then I get home, and I tell myself that that was dumb, and that I need to update my behavior - and that physically punishing myself for not going to the doctor is not an efficient use of my energy.
So I punch my hand through a mirror.
NOW, finally, I have an excuse to go to the doctor - so I wrap my hand in bandages and go back to bed, instead.
What do you do when your computed probabilities and utility function have NO EFFECT WHATSOEVER on your actual behavior?