Depends on the sort of movie. If it's something readily explainable, like some regular maniacal murderer, then stamina and being generally incapable of hiding silently will probably get me.
If not, then I have a paralyzing ability of trying to rationalize whatever I see. Ooh, ghost is possessing my friends and making them kill each other? Hmm, nah, must be an optical illusion, and the... Uhm, sleep deprivation in combination with intense fear. How's that for reason, gho- *is killed*