Panic
I suspect panic is as likely to result in a "freeze" as it is to result in irrational action. I have never seen the latter but I once had a student pilot freeze at the controls while on final. It took some time to prize his fingers off the controls.
I also saw a pilot in a light aircraft ignore the instruments while he stared at ice building up on the wing with his mouth open. A sharp reminder to concentrate on keeping us upright was all that was required.